I started breeding guppies 2 years ago, when I decided to get garters. They are very easy. You can google for detailed care sheets, but as long as they have lots of sand, for beneficial bacteria to colonize, hard water, and plenty of plants (you want both fast growing plants, and slow growing ferns to both clean & buffer the water chemistry, as well as to provide cover for the babies.

Pet shop guppies rarely look healthy, mine are over four generations of spoiled rotten healthy fish.