Hi,
Im a new user of Arduino and I don't understand everything.
I have a project to do for school and i don't know how to do it.
How can I connect an accelerometer to a ARDUINO UNO ?
Thanks for help.
Thibaxx ;D
Jumper wire or solder.
Seriously, if you want a proper answer, you need to provide more details, or try Google.
Enghien-les-Bains, huh?
Edit: That's twice you've posted a not very nice insult, and twice I've deleted it.
Next time, it will be a ban or a note to the lycée. Or both.
If you want help, you have to tell us what accelerometer you have in mind.
Read a tutorial, try it , then ask 
There's no point writing an already existing tutorial here.