If you have the ability to I would recommend attending seminary. It is the best place to learn the Gospel, and builds discipline and testimony to set the goal of waking up early each morning to attend seminary.

I can't attend seminary or meet with anyone from the church until I am 18. My parents won't allow it.

First off - I don't want you to get in trouble with your parents and trying to get you to do things behind your parents back. Honoring one's father and mother are important - even in situations like this. 
 
Given that - there are lots of things you can do - esp via the web. There is a wealth of information on mormon.org. If you can get the church magazines - you might want to consider getting the New Era (for teenagers) or the Ensign (for adults). They are online also. There are two manuals that we use on Sundays that I would recommend. One is the Young Women's manual (I think the current one is #3 here: http://lds.org/manual/young-women-manual-3?lang=eng ). The other is the Gospel Principles manual ( http://lds.org/manual/gospel-principles?lang=eng ). Those would be two very good resources for you to read. 
 
Most important though is daily scripture reading (esp from Book of Mormon and New Testament) and daily prayer. Even though you don't have the opportunity to go to church and seminary now - the Lord will understand and will help compensate in other ways.  
 
We are all happy to help however we can.

As jett said if your parents prohibit attendance at seminary then you must respect your parents will, in this matter.  
 
When you reach 18 you still must honor your mother and father as well, though you still are free to choose to be baptized and attend institute (similar to seminary for young single adults).  
 
Remember that it may not always be easy to live your faith if your parents are adamantly against our Church. I know from experence myself, it is a fine line between standing up for what you believe and still showing honor to one's parents.  
 
The great news is through Christ like love all things can be conquered and in the end all will have a change to accept the restored gospel in this life or the next.

Jett's response to Natalie is very disturbing to me as a parent. It certainly seems to support the idea that the only families that are important to the LDS church are LDS families. Wasn't Jett's advice telling her to do things behind her parent's back?  
 
Where I live, adolescents are a prime target for recruitment into the LDS church. It is well known among educators and psychologists that this age group hasn't fully developed mature rational decision making skills. And the LDS church certainly has a well oiled machine when it comes to promises for a happier life as a Mormon, so impressionable teens are easy converts. But I really don't think the strife it causes in their families is God's plan. Recruiting other people's children is simply inappropriate.

My intent was not to show how to go around one's parents to learn more about the church. The reality is that the church is very careful in these kinds of situations. If the missionaries or church leaders know the parents are very opposed - they are very careful to respect the parents wishes. We as a church are very aware of the role and responsibility of parents and will not do things for minors in an underhanded/sneaky way. We will always take the position of coming in through the front door. 
 
My suggestions was going on the assumption that the parents would not allow physical participation in meetings, etc - - but that the parents didn't out and out ban reading, studying, etc. We will always respect the parents wishes until the youth are 18 and legally can make their own decisions.

Of course it is never part of Heavenly Father's plan for there to be strive, pain, or suffering for any of us. 
 
Unfortunately these things happen on a very frequent basis because people refuse to follow the commandments and live in example of the Teachings of Jesus Christ.  
 
Jett was suggesting other ways for Natalie to continue her studies of our faith, with her parents blessing, besides attendance at our meetings or seminary.  
 
Personally I think it is a terrible parenting position to refuse to allow a teenager to fellowship with morally upstanding young men and women. To separate a teenager from a moral foundation based upon self respect and purity because they do not agree with the doctrine of the LDS Church is silly in my opinion.  
 
If the parents decide to keep all contact with the LDS faith away from there daughter that is there decision to make ( a poor one in my opinion but one that Natalie definitely should respect) 
 
Now once she turns the magic age of 18, that is a totally different story. At that point she is a legal adult and has full right to associate with whomever she desires, and really if her parents are dreading her joining our faith and living a lice of purity and service to there fellow man, I fear the associations they desire her to make as an adult.  
 
You are correct though that adolescents are a prime "target" they have humility and are seeking more knowledge. This is the perfect investigator for our faith without humility and a desire to learn you cannot find the spiritual fruits that the Book of Mormon offers.  
 
This is why Christ said to enter the kingdom of God we had to learn to be like Children, as a young adult they are in a prime position to receive and learn the truth to the restored Gospel of Jesus Christ.  
 
Most adults are not in this position our pride and arrogance get in the way, and the spirit is drowned out by our selfish nature.  
 
My question to you though ess, is why so much anger?  
 
Like Natalie's parent's seem to be why all the anger toward your fellow man?  
 
What is so terrible about our faith that it requires such negativity?  
 
Did not Christ say that all who are not against me are with me? (Luke 9:49-50)