I have from NEXUS get a file, done what i do whit other files, go to Data in falllout and put it there, but it dont work, ? what do i have to do?

it is a FOMOD file others that work is .esp

Open FOMM, click the Package Manager button. When the Package Manager opens up, click the Add FOMod button (you may have to select the option from the dropdown menu). Then browse to the zipped up FOMod and open it, say "yes" to the "copy file to FOMod directory" prompt, and wait a few seconds. It will show up on your list of FOMods. Highlight it and click "Activate". Seems like a lot of steps but it isn't really any harder than installing a mod the normal way, plus it comes with some cool features - easy uninstalls, version checking, file reordering, etc.

Thanks for the help, i didnt have FOMM, but now i have.