How do you get 10 minikits in Lego Star Wars secret plans

You have to find them in a level. If you want to get all of them, you should play the level to get through it, then come back in Free Play mode. You will need to find secret passageways to find them. When you collect all 10 minikits, somewhere in the Cantina you will find a monitor displaying your minikits. It will show you the vehicles and other things you have made using minikits.