Verified answer

Start with a dirt bike. It sounds odd, starting with something with 2 wheels instead of 4, but bikes are more controllable then ATVs (They are lighter and shifting your weight has more effect on a bike). Also, the problem with ATVs is that if you start getting air at all with them, if you don't hit the landing absolutely straight they throw you off and try to kill you, where as bikes are a lot more forgiving. The shifting on a bike is the same as an ATV.

How shifting works on either is, starting in neutral, you press down once to get into 1st. After that its up one full pull to get to 2nd, up again for 3rd, 4th is up again, etc. To get back to neutral you need to be in 1st or 2nd. In 1st, half a pull up to get to neutral, from 2nd, half a shift down. Don't forget about the clutch when shifting.

How I like to think about the gears is like this;

6

5

4

3

2

1.5 - neutral

1

You pull the shifter up once to go up one gear in the list, push down once to go down once on the list, and neutral (being 1.5) is a half shift away from either 1st or 2nd.

Now the reason for neutral on anything is so you can let the clutch out and get off with the vehicle idling (running) without it being in gear and driving away by itself. If you let the clutch out in gear, its going to move.