This video shows how to attach the flags to your whip chain. You need flags ( plastic is better than silk ), sticky tape and of course a whip chain. Silk flags look good, but most people use crumpable plastic flags, becasue they clatter loud and make it easier to control the whip ( slows it down ). Buy the sticky tape in a drugstore.

The flag should be square size of the last 2 sections of your whip.

Attach the front flag with 4 pieces of sticky tape to the last 2 sections of your whip. Each piece of tape should be finger length.

Attach the 2nd flag to the handle.
For most techniques the second flag doesn't matter, but originally the whip chain has 2 flags and there are a handful traditional techniques where you release the handle for a moment.