How to grow a garden on minecraft?

You need a water source, soil (or sand depending on plant) and a garden ho. You til the land near a water source, generally up to 3 spaces away. Then you plant the seeds in the tilled soil and wait. Make sure there's a light source also, either the sun or torches. For sand it can be anywhere unless it's sugar cane, then it needs to be directly in touch with water.

It depends if you want a garden or a farm. If you want a garden of flowers and grass, get a bone, craft it into bonemeal and right click with it on grass. Other wise do what the other guys said.

Firstly, you need seeds. Punch grass and some seeds cone out. You then need to craft a hoe. Next find an area with grass. You need to right click with the hoe and it makes the dirt with grass brown. Click with the seeds on the grass which has been hoed and let then grow until fully grown into wheat.

You can't really grow a garden in Minecraft, unless you accquire a lot of bonemeal and randomly right click grass blocks. It might grow into flowers or tall grasses. Other than that, I suggest you go around your world, collecting flowers and planting them where you want them to.