I guess you need to decide if you want to show a general beam in which case i just draw a wall and use the wall tool with the dimensions of the beam. 

If you want to show an 'I' beam or 'C' beam then on the side of an object use the foundation tool and reduce the control point size (so that they are not to big) and mark out the profile of the beam.  Then copy and paste this section to where you want the beam and then scale the Y dimension to the desired length of the beam.

Should be on the context bar when you click on a foundation object....the version on the website should be a later version - just make sure you are installing it to the correct directory -as it will create another directory by default (you may have to delete this extraeneous install)

(Context Bar-the transparent bar at the bottom of the screen that you can turn on and off when you press the space bar) This bar shows options for the tool you have selected and the object you clicked on.