Hi Artur_Vadim--the French is an enormous system and you can vary the game greatly as early as the third move. By pushing 3. e5 you lock the center and lead to a slow opening where your pieces gravitate towards a kingside attack. Whereas 3. exd5 is a very different move that lets both sides develop easily while still keeping that extra tempo from moving first. There's also 3. Nc3, leading into any number of systems, and even anti-French options before that like 2. d3, 2. g3, 2. c4, 2. Qe2, etc. It's hard to tell you what to do without knowing what's difficult about it currently. Try this, which is a (*huge) e-book outlining lots of different great ideas:
http://www.ericschiller.com/pdf/FrenchDefense%20from%20WCO.pdf
I have been playing a lot of games at my chess club and there is one strong player there that will always play the French as black and Im always at a loss for ideas on how to fight this opening.
Anyone care to share how they play against the french opening?