any advices about English training center

Try the British Council, off Gargaresh Road near Regatta camp.

I don't know if it's the best, but if British Council is over your budget you can try:

http://www.aletc-libya.com/adult.htm

I met a couple of the teachers from there and they seemed pretty good.

Otherwise, visit this link to get a list of centres:

http://www.eslbase.com/schools/libya

British Council

try the Berlitz Centre downtown in Mezran, they teach basically conversation classes in English and  they are realy good.i tried the arabic there, it helped me a lot, i can buy the groceries from the corner shop and the guy actually understands me now:).

Is there a center for learning English in Benghazi?

Contact AFAQ UTG - On Regatta, they can help.