How to install Minecraft mods?

It depends on the mod you are trying to install, but… -Install WinRAR or another archiving software -Download the file along with modloader, modloaderMP, audiofile, and sometimes forge -Open your minecraft.jar with WinRAR and just drag the download files into your minecraft.jar Be sure to back up your saves and bin first

First you need to know which mod you are going to install. Anyways here is a method that will help you to install mod:

Windows Vista/7:

• Click Start | In Search Bar, type %AppData% and press Enter.
• Open Roaming | Open .minecraft.
• Open bin | you will see minecraft.jar (It may appear only as minecraft).
• Open folder using WinRar. To do this, right-click on minecraft.jar and hover to the Open With menu.
• Copy class files into this folder | Exit the folder once you have copied class files. Certain mods will require you to copy files into other directories. For example:
• • Resources folder (found in the main .minecraft directory)
• • Config folder (found in main .minecraft directory)
• • The .minecraft folder Also Follow the instructions on your download for clarification on where to copy files to.

Also make sure that minecraft game is lag free and bad video card drivers problem doesn’t occur as after installing mods the game become heavy and graphics problem occurs.

If you are in such situations then try to take some optimizing steps mentioned in this website:

http://www.MinecraftLag.com