It is been a year around since I have a boyfriend. But still i cant have orgasm.( In fact i didnt have much (very limited ) experience before) I've been studing a lot of materials. My partner say that I am a bit shy. infact I am not. I feel very  free.  But still there is no result yet. I think the problem is with my "head". Maybe i am controlling myself more. I say it because i follow every process of the sex. 

How can i get rid of it. Sometimes i think I'll get orgasm if I'll get too drunk. then I will not think of anything and respond to the process only physically. How should i prepare myself mentally.

Sex shouldn't be a process, or a routine. I can understand how it does feel like that if you read material from a book or website. Remember that everything you read is simply guidelines to help out, not a method that should be followed to the letter. Always do what makes you feel nice and comfortable.

I don't think drink will help. Also, there's no need to prepare yourself mentally. Sex shouldn't be something that you have to prepare for like an exam or a sports match! Sometimes if you think about it too hard, you become worried and stressed about it. Especially if you focus too much on needing to have an orgasm, this can cloud your feelings and make you tense and nervous, because of the fear of failure.
Instead of orgasm, just think about pleasure. During sex, relax and enjoy yourself, and do what feels pleasurable. Before you have sex, tell yourself this - that you will accept whatever happens on that day, whether or not you have an orgasm.

Presumably you have already tried clit stroking, maybe also try G-spot massage.

You haven't mentioned whether you can have an orgasm on your own, so if you haven't, then I advise trying that first.