Hey there. I have found this guide pretty useful:
https://github.com/FlimFlam69/WiiUTutorial/wiki
It takes you through all the steps necessary to install Haxchi and Mocha. Since you can already boot into rednand, you may be interested in the "Brazilian Title Install Method". You can basically grab pretty much every title, directly from Nintendo servers, and install to your Wii U. This includes updates, DLC, eshop games, vc games etc. I strongly advise you to use USB for loading games... you can also use Loadiine to run games from SD cards but this is kinda outdated and brings some issues with several titles (since SD card reading speeds are much slower).