How do I charge my iPad - I have a USB cable, and three plugs

http://www.apple.com/shop/buy-ipad/ipad-pro

The 12.9-inch iPad Pro comes with a 12W USB Power Adapter. The 9.7-inch iPad Pro, iPad Air 2, iPad Air, iPad mini 4, and iPad mini 2 come with a 10W USB Power Adapter. If you need to purchase an additional adapter, choose the 12W adapter because it can charge all iPad models.

I know yours is an iPad Mini, but this still answers the question...

What do you mean by which plug to use? You can only insert the cable into the iPad with one end and that is the lighting connector - the small end. The other end is inserted into a USB port on your computer if you want to sync, or into the power adapter if you want to plug into a wall socket to charge the device.

Why don't you use the one that came with the iPad? 😕