Hi Rick,
I'm guessing you mean FIRST FRC Team 3951? You might want to post further questions in the FIRST discussions group.
Hopefully David's response got you on the right track.
STP files are usually 3D. You can modify lenghts of those in Creo 2 using the "Flexible Modeling" tab.
As David mentions, you can also create a new extrusion selecting the end surface as your sketching plane and use the offset edge (loop) button with a value of 0 to extrude that x-section to the desired length.
There are several other methods when using DXF files that we can talk about if you need more help.
Hope that helps,
Josh