As with many plants, cactus need food, light, and water. You would think that cactus would not need water, but if a cactus is in a pot, it needs more water than if it were in the ground. You are supposed to keep the soil around your cactus moist -- not let it dry out.
Here's a good link for you:
Cactus family includes at least 2,000 species. They can be raised equally as well in the garden as in our house. They do not need a thorough care. They do not need water almost at all, the only thing needed being the sunlight.
The first step in growing a healthy cactus is buying a healthy cactus. Do not buy a cactus with broken thorns, damaged or that has an irregular growth. Cacti can be bred from seed, but thir development and growth can take more than a year.