Wrong forum, if you're asking about 1stGen WoE.
This is the SF2 Forum.
However, having said that, let's see what we can do...
1) on Win7 do NOT use the default to usual C/ProgramFiles...blab balh balh location for install
Use the ROOT of the C/ drive for 1stGens (C:/Wings Over Europe) (this is covered in the 1stGen Knowledge Base somewhere)
2) 1stGens to NOT create mods folders -- only the SF2 series does, so all your files will be INSIDE you main install (C:\Wings over Europe
3) From this point, assuming no difficulties in installing or moving the game to the root of C, and adjusting the shortcut accordingly, and the game does run (don't forget to reinstall DX9, and it'll probably be needed), you can now start adding mods as described in the readme of your downloads