hey, i'm new to it as well and i managed to get lha working
/me nods to vince_AC
double click on the hammer icon with LHA written under it, and then it should say some crud like, enter command arguments, it's should say LHA already, so you should have this typed in b4 you press enter
LHA X filename.lha
(replacing filename, with the filename :-) )
that's it! [that's the simplest method of using lha, i've never had to use anything else, though this method will extract to the current directory and then you will have to move it somewhere...
