First off; Welcome to The Swamp.
Second; What make and version of CAD do you have? Some older versions did not have the
cut/copy & paste feature.
Third; You should be able to go to EDIT pull down & select the operation you want, just follow the instruction on the command line at the bottom of the screen. Then go to the drawing you want to paste in and go to the EDIT pull down menu and select the paste operation you want.
Fourth; if that fails, look up the command WBLOCK (that is if you are running an Autodesk Product) in help and follow the instructions. A tried and true meathod.