OK, I'll tell you a step by step tutorial to using User Content Alpha
1.) Download UCA (user content alpha)
2.) Put it in your add-ons folder
3.) In the main "Blockland" folder, make a new folder called config (if you have one, that is fine)
4.) In the "config" folder, create a new folder called "content"
5.) In the "content" folder, create a new folder called "data"
6.) In the "data" folder, create a new folder called "shapes"
7.) In the shapes folder, place your new brick textures.
9.) PLAY BLOCKLAND
10.) Realize that I skipped 8