There are a couple steps needed to. Not very hard to do, but kinda confusing your first time.
1. Download the link of the Texture Pack provided by the maker.
2. Place the file on your Desktop, or easiest place for you to find it.
3. Open up Minecraft from the launcher(For me i have to do this)which should be on your desktop if you downloaded minecraft.
4. In the main menu there should be a Texture Packs or Mods option, click that.
5. Open the Texture Pack folder from the lower right.
6. Drag the Texture Pack into the folder, and close the folder.
7. Look back into Minecraft Texture Packs or Mods option, and it should be below Default.
Note: You should try downloading the HD Texture Pack Patcher if you see a thread on this forum saying something like that. It'll let you use the full extent of Texture Packs.