[cctalk] 3D Printing

Are there any 3D printing experts hanging around here?  I need help. I want to print things like a bracket to mount my FreHD in a disk bay. Some other things, too.  The problem is the STL file wants to print these items vertically instead  of laying flat on the table.  Needless to say by the time it gets to the part where it wants to print the faceplate the object is unstable or, in some cases, completely tipped over. Is there any way to change the orientation of an object on the table using just the STL file? I have a Creality Ender 3 printer and their slicer software. bill