Ok im doing the "My first Vault" tutorial seroius and there is no vault 108 for me to find when i need it

"The first thing we need to do is create a new interior cell. The best way to make a new cell is to duplicate an existing one. To do this, make sure the "Cell_View_Window" has "Interiors" selected in its "World Space" drop-down box. Now find "Vault108a" in the list of cells."

It also says that it may mention stuff from F3 but it should be ok.

OK, it's irritating but don't worry, the tutorial will make you work on vault74, and you have it in New vegas.
Yes, Vault 108a is in Fallout 3 but you can duplicate any other vault, it makes very little difference. They all share the same resource and look very similar (you can even rename your duplicated cell Vault108a if you want). As the tutorial will make you create everything except the walls, the starting cells are not important. Once you begin you'll understand very quickly.

Good luck