Trouble installing MINECRAFT mods. PLEASE HELP!!!

So I recently saw a tutoial involving how to install minecraft mods. It said I need to access the minecraft .jar file. The problem is that every time I try to "open" the file I get an error. I even installed this program called WinRAR but every time I right click the .jar file and go to "open with..." option there is no option to open it with WinRAR. Is there any way to install minecraft mods without accessing the .jar file?

I'm not very computer savy so try to take it easy on me. :)

Any help would be greatly appreciated.

You have to be able to open the .jar file to mod MC. I recommend 7-Zip over WinRAR, it's lightweight and much faster than anything I've ever used (and totally free).

Right clicking > Open with... should have an option on the bottom that says "Choose default program" and from there should open up a file browser. Click around until you find the .exe of whatever zip program you want to use, and anytime you open it in the future it should use that program.

I think I may have solved the problem. The only thing is that spawnlist hasn't got an update for v1.5 yet soI can't test out my baby animals mod.