Some information about CastleCraft Resource Pack 1.7.6/1.7.5/1.7.2/1.6.4 that you can need before installing

How to install CastleCraft Resource Pack for Minecraft

In order to use this texture packs properly you will need to either patch your Minecraft using MCPatcher or using OptiFine. Optifine is preferred as it includes all of the features of MCPatcher, and greatly increases game speeds and graphics settings. MCPatcher tends to be updated on the same day as Minecraft updates, so use it instead if you are in a hurry. ...

Detail and Download here : Minecraft mods 1.7.5/1.7.2/1.6.4