Fenring made a very good tutorial, please read it carefully. And if questionmarks still are left, register a user at bfeditor.org and ask there, you will get answer within hours. Even though BF2 modding is pretty dead except established mods like FH2, PR, XWWII etc, there are still hordes of dudes roaming that forum and they like to help out (as they don't work on any mod).
I just reinstalled my mapping PC, installed Bf2 + patches + FH2 + editor and could start mapping in 3minutes, it is not a big deal.
1) make a copy of the fh2 folder (rename it fh2MAP for example)
2) install Bfeditor
3) extract the files like fenring explains
4) start editor, load fh2MAP mod
5) map
honestly, that's all you need.