I need to create a new beam type in openbridge. How do I do that? I need slab beams.

I need to create a new beam type in open bridge.  there are two different sizes.  one is 12" tall X 3'-11.75" long and the other one is 12" tall x 4'-11.75".  In Texas they are called slab beams, but I am not sure how to create two new ones.