Your kindle must already be modded. Follow the instructions here to mod it.
First-time installation requires a PC. Download the github repo and extract it into your "extentions" folder on the root of your kindle. Then use as normal.
To learn how to disable OTA (amazon) updates, follow the guide here you want to do this so Amazon does not disable your mod. Use either the "rename ota bin" extention, or try update block. If your kindle firmware is below 5.10, you can just create a folder called "update.bin.tmp.partial" in the root. (make sure it is set to read only.)