1... do a search! there have been loads of recent threads on this subject!
2.... Fibreglass will have an invisible film of mould-release coating it. hot dish-washing detergent and a Scitchbrite scrubbing -pad is the way to clean it....rinse thoroughly,wear vinyl or latex gloves to handle the dry canopy.
rattle-cans are a cheap intro. to painting (car accessory shops or hardware stores) be sure to practise "swinging " the can in even strokes ,keeping it square and an even distance from the surface....many fine coats are wanted....trigger the canas you spray....start stroke to one side of "target"-swing, press button as it gets to target.....release as stroke passes target...repeat , either by reversing swing, or go back to start...aim for each pass to overlap the previous one by about 1/3the width
DON'T wiggle it around in little circles!...it's NOT air-freshner or fly-killer!
Allow to dry thoroughly between coats...if flatting is needed, it should be at least 24 hours after the last coat(assuming a warm atmosphere).
Preparation and cleanliness are paramount.
after painting, to protect the finish, rattlecan clearcoat is OK for electrics but Nitro's will need a 2-pack clearcoat....the easiest way is to find an auto-body shop and ask them to fit it in with their next clear-job (will probably cost $10-$20,cash in hand!)
hope this gives you some idea...there's more to it than this brief outline,but as I said....search! (top of page, "canopy painting" should give you a few nights' reading, the skill takes a few years, though!