Listen to the sound of the engine, and look at how the sound relates to the rev gauge. You can do this while parked, with the car in neutral, so long as you’re on flat ground.

The car speed (or wheel speed) and the engine speed are linked by the gear, and detached by the clutch.

In order to avoid grinding the gears, you want the engine speed and car speed to match up for that gear.

Luckily, you don’t need to be perfect!

For example, let’s say you are in first gear, and you’ve gotten the car moving a little. Let’s say you’re driving at 20mph, and that your tachometer says you’re at (I’m guessing here) 6000rpm.

You push the clutch in and take your foot off the gas. The tachometer starts to fall. Try to get into 2nd gear before it falls all the way to idle. If you mess it up, and it drops, that’s fine. You’ll need to give a little gas to get the engine spinning (let’s say 2000rpm) and then come slowly off the clutch.

You’ll either hear the engine whine because it’s not spinning fast enough, or the car will lurch forward because the engine is going too fast.

If you are careful with the clutch, you’ll feel which way it wants to go, and you can adjust with the gas until they’re both happy. Then you can come fully off the clutch. you’re in 2nd gear.

Good luck