Here is a useful link for installing your Resource Packs in Minecraft
To summarise:
- Download your desired Minecraft Resource Pack from the web. Do not unzip the downloaded folder
- Open Minecraft
- Go to "Options", then "Resource Packs"
- Click on "Open Resource Folder". If the window doesn't open, you'll have to find it manually through the Folder Explorer.
- For Windows: %AppData%.minecraft\resourcepacks
- For Mac: ~/Library/Application Support/minecraft/resourcepacks
- For Linux: ~/.minecraft/resourcepacks
- Once here, drag and drop/copy and paste your unzipped resource folder into this directory.
- To be safe, restart Minecraft.
- Go back into your Resource pack list in Minecraft. Here you should see your new Resource pack in the left-hand list. Click on it once.
- An arrow (->) should appear. Click on it and it will be added to the "Selected Resource List". Double click on it again to activate it!