If you have access to SolidWorks you can simply import STEP product data (.stp, .step) to the program and save the data as one of the part files (.prt, .sldprt). Without SolidWorks, you have to use some of the other alternative CAD software with SolidWorks format support, or some kind of dedicated CAD conversion solutions.
Open STP file Open SLDPRT fileA set of 3D modeling tools
A CAD converter with huge format support
A CAD visualizaton, analyzation and translating system