Why are there deserts?

This question is related to the CHANGE OF THE ATMOSPHERE AROUND THE WORLD, or maybe because of the LOCATION OF THE LAND.

Hot air picks up and drops moisture over the line of the Equator which spreads both ways, north and south. Along the Tropics of Cancer and Capricorn, the moist will cool and sink back to the Earth's surface. As these masses of air are very dry when they begin to come down, they bring no rain to these areas. When they reach the ground again, they will spread through the Equator, where the air is transformed into trade winds,going towards the poles. So finally, two parellel desert belts will occur along the lines of the Tropics.

Some large pieces of lands are located in the middle of the continents, which are too far away from the sea so that no moisture can reach them. Why is this? The winds have dropped all their rain, so there is no more to drop for the places which are so far from them. But simply, how are deserts formed?

Let's see the steps below, and we will know how it is formed:

1. Rain falls on the ground

2. Some of the water evaporates

3. amount of water that evaporates > amount of rainfall

4. A desert is formed!!!!!