This section of the forums isn't for asking ROM hacking questions. If you're having an issue with a particular hack, you should ask
in the hack's thread.
As for opening the download file, you need the program Lunar IPS. There are tutorials online for how to patch a ROM file. (If you need help with that, feel free to ask me, as I've used that program before.)
As for finding a clean FireRed 1.0 hack, your best bet for that is to search on Google. The PokeCommunity forums does not allow linking to hacks in any way for any reason, so you'll have to find it yourself.
If you have any more problems with getting the hack to work, ask in the thread for the hack so the people who've made it/played it can see it and answer.
Hope you get it to work soon!