How to Apply Cheat Codes in Dolphin Emulator

1. Edit XFB Settings
A quite of bit of codes won't work if the XFB settings are not correctly configured.
Launch Dolphin Emulator. Click on the Graphics Icon/Logo at the top (looks like a Computer Monitor). A menu will pop up. Click on the Hacks tab. Underneath 'External Frame Buffer (XFB)', UNCHECK the box for 'Store XFB Copies to Texture Only'. Click the close button on the bottom right to exit the menu. Reboot Dolphin.

2. Set ISO Directory
If you haven't yet, you need to set the default games directory for dolphin. In the large empty menu, you will see..

Quote:Dolphin could not find any GameCube/Wii ISOs or WADs.
Double-click here to set a games directory...

Simply double click anywhere inside the large area. A menu will pop up, navigate and click on the folder that contains the ISOs you have/use. Click Choose, then the empty area will fill up with your list of ISOs.

3. Apply Cheats
Right click on the ISO you want to apply cheats to. A small drop down menu will appear. Click on Properties. Another menu will appear. Click on the Gecko Codes tab. At the bottom left, click on the Add Code button.
For Name, ofc fill in the code name.
For Creator, put in the creator of the code.
For Notes, add any notes that you desire.
For Code, put in the actual cheat code itself.
Click Save, and you will see that the code is added to the top box. It will be displayed via the code name you gave the code, and will be checkmarked. To add another code, just click the Add Code button again and repeat the process.
Click Close. Then launch the ISO. Codes are applied. Congratz!

Notes:
To see the code's contents after adding it, simply click on the code name itself. It will be highlighted in blue and the contents will be shown in the lower box. To not have a certain code be used, click on the checkmark to remove the checkmark from the box.
To delete a code, click on the code name. It will highlight in blue, click the Remove Code Button. To edit the code instead, click on the Edit button.