I can use my character of fallout3 in fallout new vegas? like a type of synchronization for play fallout 3!!

No, Fallout 3 is not affiliated at all. Your character will not be brought into FONV. You start fresh, shot in the head twice, and left for dead.

you will probably be able to recreate the look of your character eventually(depending on whether he/she was modded or not), but beyond that no. Some people are planning on making it the same character (in their heads), but it won't affect gameplay in that way. New start, new character, level 0.

no you wont be able to that its a complete new game.