It sounds a bit suspicious to me. Do you have ability to login as admin? It sounds as though you don't & you don't have permission to install on the computer. Is it your computer or your dad's? It doesn't sound like a LW issue. If not, it would probably be best if you asked permission from the owner of the computer if you can install LW. I might be wrong but I get the impression you don't know a lot about OSX. It's certainly not OSX 9. If you have a dual OS, why not dwnld & install the classic version LW. I noticed you posted in the general mac section also.
Actually having another look at this, if you are in OS9 as the topic suggests & you have a security system. This won't be a native mac security system but 3rd party (as far as I know). Which means that what I said earlier is most likely true. It's probably not your computer. To reiterate, it'd be best & fairer to ask the permission of the owner.