where is obd port?

[mcfc11]

hi there, i have a c200 1999 and im getting very rough running when cold, i have carsoft 7.4 to diagnose the problem but can not find the obd port on the car, i have looked in the engine bay and under the steering but cant find it anywhere, can anybody help please.
thanks in advance..

 

[Ellsy Tanners]

You have a 36 pin diagnostic plug on your model, under bonnet back right, in module box under round cover.