I get that you sell keycaps but what about the keyboard itself? Also, do I need those things that go under the keycap as well? Sorry, Im a keyboard N00b but I would like one. Im just a little intimidated here by the fragmentation of products.
Pretty much what @jbozsworth said here. You would either need a fully built keyboard (and swap just the keycaps to these) or a barebones kit sourcing any other needed components (will need case, PCB, switches, stabilizers, and keycaps at minimum - some of which will be included in the kit).
This guide that @The_Manic_Geek just posted might be a helpful starting point, along with the intro to switches that @ThereminGoatMK put together. Let us know if you have any other questions or need any additional help with the process.