Welcome to the Learn Dothraki forums!
Although things are a bit slow here right now, there is a lot of good study information available to help you learn (and although I have been here a while, I am just starting to really learn, as well). Check out the wiki and the dictionary threads under 'language updates'. There is also some good material under 'beginners', and hidden here and there throughout the forums.
There is no formal way to learn Dothraki yet, but it will come in time. In the meantime, just bite off what you can chew.
Enjoy!
