Prerequisites (install first):
- Minecraft Forge - I recommend installing the recommended version. Make sure it's for the right version of Minecraft.
- Gases Framework - Included in the download package. Extract along with the other files.
Installation:
Open the .zip archive from your download in the application of your choice, and extract the .jar files into the mods folder located in ".minecraft". If this folder does not exist, you have to run Minecraft Forge once, then install. Remember to delete any previous versions of the mod!