There were no 1991 C200s, but assuming it's a C200 W202 of late '90s vintage, you just need a 10mm socket and ratchet, or a spanner for that matter, and undo the nuts, and then squeeze in the tabs to release the reflector, having removed the bulb holder to start with.
A 5 minute job.
But make sure you buy the correct lens as there are 3 different types.