Calculating VAT prepayment based on previous quarter

I basically know the principle of making payments of VAT based on previous income but I don't know how to do the calculation. I couldn't find instructions on the internet so if someone knows where please let me know, or give me a formula. Otherwise, here is an example if you can give me an explanation.
- At the end of quarter 1 you get a report that you have 200 € left in your favor (overpayment).
- Sales during quarter 2 have 1000 € of VAT attached to them.
How much do you need to pay during quarter 3? Or is additional information needed?
If this is a dumb question don't tell anyone ;-)