[ Video & Online Games ] Open Question : why cant i install minecraft mods?

ok so I have WinRAR and everything but when I try to drag the mod files into my jar, my mouse turns in to a "no" sign...you know the little circle with a diagonal line through it...I tried to get magic launcher but it says "modified jar file,the mod may not work correctly"..please help"

Source: http://answers.yahoo.com/question/index?qid=20130105135955AAVUGwp

Justin Bieber Katy Perry Jennifer Aniston