Molecular cloning requires some method of screening colonies for the presence of an insert. Traditionally this has been done with restriction enzyme digest; however colony PCR can accomplish the same thing in less time and for less money.
The key steps to colony PCR are:
1) design primers to detect the presence of your insert;
2) set up a standard PCR reaction (primers, dNTPs, polymerase) using the supernatant of lysed bacteria as template; and
3) run your PCR product on a gel to analyze product size.

The first and perhaps most important step to colony PCR is designing primers. There are 3 strategies for primer design:
1) insert-specific primers,
2) backbone-specific primers, and
3) orientation-specific primers.  

(for More details, go to Documentation section: “Strategies for Colony PCR”)