My wife and I painted our finish basement floor.
There are several manufacturers of concrete paint. Most come in white and you can add pigments for the color you like. Check with your local paint store or home center on this, usually they are the ones who do the mixing and would likely be included in the price of the paint.
Some paint need primers and some are all inclusive. The quality of paint you need would also depend on expected traffic on your porch floor.
The toughest part is preparation. Most concrete foors are made with some sort of lye material which needs to be neutralized. If this is not done, your paint will peel off. You need to use some sort of acid, usually muratic. Caution it is dangerous and may burn the skin, use acid protection gloves and eye protection. It can also burn other stuff like furniture and such. Clear everything from your porch. Follow directions to a tee. There are also several comercial products which are a bit less nasty and usually do the job, depending on how much lye there is in the concrete. We used one in our basement because there were also less fumes than muratic acid, which also requires good ventilation for its use.
The best suggestion I have is to get advice from your local paint store or home center. Some of them sometimes have pamphlets with step by step directions.
Good luck.
