Brep command

Hi! I’m in a bit of a time crunch and I’ve been working on this assignment for a while but cant figure it out. The assignment is to make a series of rotating boxes. I have the boxes, but now I need to replace the boxes with a mass model that I have. I know that i need to use the brep command but it doesn’t attach to the point. I’m new to the program. please help!
attached is a screenshot of what i have for the box and need to fit the brep command somewhere.

i got the brep to rotate around itself at 360 degrees, but i need it to be on the c-plane and in the x and y direction