Fixed Grids/Locking Objects to Positions

This is kind of an involved question. I’ve just started programming with OpenGL and want to implement a system like Lego™. Are there any “easy” methods to do something like that in OpenGL, or is it going to be an intricate and well-fought battle? I don’t want specifics, I’d rather have a few hints on where to go and what to look for, and be able to figure it out for myself. Thanks so much!