use a hack saw to make a slit in the pipe, or a Sawzall,
open the slit with a screw driver,
then use your tin snips to cut the pipe in a circle.
tin snips have different colored handles
yellow is a straight cut
red is left-hand cut,
green is right hand
after you cut the pipe, you will need a crimping tool to make a crimp so the flex hose or pipe will fit over the pipe you cut
that looks to be a dryer vent, DO NOT use screws to hold the pipe together, screws catch lint and are a fire hazard
buy a roll of SILVER duct tape, not the regular gray duct tape