Welcome Leonardo!
Stop frame animation using Lego sounds like a lot of fun and i bet it looks awesome! Would love to see some of your work if you have it online? You could post it as a thread in the 'Off Topic' section of the forum. Its always good to see CG being used in other areas and it would be great to see the results. We recently had a lego themed competition here and everyone loved it so im sure people would be interested to see your stuff.
I've never used Blender before so dont think i can advise you on anything there. Is it textures you are looking for or settings for the material editor? if you post your work in progress here im sure you will get all the help you need
