Mirror section of part?

I'm a newbie to Solidworks and this is my very first design.  I'm trying to create a bracket that I want to eventually save as an STL, slice it into gCode for a 3D printer.  I designed most of it and attached the Solidworks drawing file below.  This is supposed to have two (2) of the clamps on each side.  I created one and would like to "mirror" it to the other side, but cannot figure out how to do this for the life of me!  Not sure if I'm to mirror a feature, entity, etc. (don't know the differences between them).

Hopefully I created the part correctly - I found myself sketching rectangles and extruding them, etc. to create the entire part - so it's sort of "in pieces" and don't know if I need to "merge" or "combine" them together.  Not sure how to do that either.  It turned out great though!  Any help and detailed instructions to correct this and mirror the "clip" to the other side would be greatly appreciated.  Love learning this!  Thank you very much!

Kind Regards,

Nelson

SolidworksDrawings And Detailing