Who can help me ? i need a sketch or something to build the electronics...

There are a lot of ideas and plans about h-shifters on rscnet, i'm sure you'll find something good there.

FF joystick

H-Pattern plate

FFShifter software

If you dont know the plans for the electronics to make one you shouldnt be asking for one.

I've built my own H shifter about 5 months ago, but it has been broken after 5-6 weeks.
I used my early racing wheel (it was a Geinus crap) for the electronics, so i didn't need to plan the electronic stuff. I used only the electronic board, the micro-switches, and the USB wire, and it worked. (Of course I had to build a body, made out of wood. The gearstick was a bared Genius joystick, and I bought the gearknob at tesco for 2 euros... The whole thing was only 5-6 euros + 4 weeks of building.)
But, after 5-6 weeks of intensive LFS driving the micro-switches broke one after the other and now only the 1st, 2nd, the 5th and the 6th gear is working.
I saw some video on youtube about handmade H shifters, and they are all using Microsoft Sidewinder USB for the electronics... Maybe it can last for more time...
Time and patient is needed, if you want to do this!!!