Ask your toddler if he needs to go potty every 20min on day one, 30min on day two and from day three every hour. A great tip is to use a timer, which helps lower the resistance comparing to a reminder from a parent.
A simple kitchen timer will do.
The seat can be placed on a regular toilet or a potty, just by folding. When used as a potty you need to put a bag. Special bags can be bought, but you can also use a plastic supermarket bag and some tissue paper for absorbing. Just make sure there are no holes.