Hello and welcome to the site! 
There are many resources on the site which can help you improve your chess:
1) Try out our Daily Puzzles (http://www.chess.com/forum/category/daily-puzzles) to test your tactical vision in solving chess puzzles each and every day.
2) Read some instructional "Chess Articles" which can be found under the "Learn" link.
3) Submit your games to our "Game Analysis" forum where you can get help and suggestions from other Chess.com players
4) Visit our "Books and Equipment" shop where you can find some instructional chess material to purchase.
5) Find yourself a chess coach in our "Directory" section.
6) Look at the "Downloads" section for some instructional chess material available to the public.
7) And finally...play some games! (http://www.chess.com/play/)
II just came to this forum, and i've been playing through the night, while i'm at work... Which books, sites, games do you recommend to improve my skills?
Thanks, and best regards