I did on paint bmw 2002 skin , but i can't use it. I ask why it will'nt work.
I put that on the filter lfs/data/skins , lfs/data/skins_dds and
lfs/data/skins_x Someone tell me why it will'nt work?

First of all you need a proper jpg with a proper name: Use FBM_myskin.jpg. Then copy it into \skins...

Tutorial: Naming your skins correctly.

He's a demo racer anyway... Fail

Quote from the_big_n00b :

He's a demo racer anyway... Fail

Stop demo bashing. He didn't mention what car the skin is for so being demo has nothing to do with it or uploading it to lfsw, just that he can't get the skin to work.

If you details exactly what is the problem with your skin then we will be able to help. General advice though-
Name the skin correctly like Void mentioned
The needs to be a .jpg image
Place the skin file in lfs/data/skins
When in lfs, select to add a new paintjob and select the skin file name.