Instructions
Download Forge
Navigate to the "Minecraft" Forge download page (link in Resources).
Click on "Installer" next to the Recommended-1.6.2 option. Click "Skip Ad."
Click the downloaded file and then click "OK" to run the installer.
Click "OK" when you receive the message that Forge was successfully installed. When you open your "Minecraft" launcher, a "Forge" option will appear in the Profiles drop-down menu.
Rival Rebels
Navigate to the "Rival Rebels" download page and click "Download Rival Rebels 1.6.2c" (link in Resources).
Click "Skip Ad" and then click "Here" to download RIvalRebels.zip.
Hover over the upper left corner of your start screen and click "Search." Type "%appdata%" without quotes and then open the ".minecraft" file.
Double-click "mods" to open the folder. If there's no mods folder, create one and open it.
Drag the RivalRebels.zip file into the mods folder. Close the folder.
Run the Minecraft launcher and choose "Forge" from the drop-down menu. Sign in with your username and password; "Rival Rebels" will open with the game.