Same as normal, just fill in your details either on the green slip if you got it or by a v62(???) form,send in your £25 if you don't have the green slip there's no need to mention anything.

Also Vic (which is irrelevant to cat d) is VEHICLE IDENTITY CHECK and does no checks on vehicle condition.

Also not all cat C's require a VIC, it's up to the DVLA.