Can't mod minecraft without it crashing?

I renamed all my files and and copied an pasted them in a new folder named 1.7.4 mods and opened json file and renamed it and then opened my JAR file deleted the META and dragged my mod in then created a new profile with the modded version and launched minecraft and it crashed so i kept trying and it wouldn't work does anybody know why?

I'd use a mod manager, and currently minecraft 1.7.4 is relatively new so mods are outdated… Btw if you're interested on how I got Minecraft or other games for free, click the link below if you're interested~

Edit: Make backups of the jar too!