Left pedal is the clutch; middle is brake; right is gas pedal. you can only change gear when clutch is down

Find an empty area to practise this. With left foot stepping all the way down the clutch, very slowly lift your leg. You will feel the car starts moving a bit. This is the point your right foot should start pushing the gas pedal.

Now left foot full down clutch, right foot on brake, enter gear 1

While releasing the pedal, at the point the car starts moving, start pushing the accelerator pedal

and now the car moves!