Or, if you just meant that you want to close the app you are using so that you can open another, a single press of the home button (the one on the front of the iPad), will do the job.
Mojosodope's instructions are for when you need to manually remove the app from RAM. This is not necessary unless you are having problems with the app. The iPad normally removes apps from RAM automatically when it needs the space. Recent apps are normally left in RAM in a frozen state. They don't slow the iPad down or use battery while in this state, but it makes switching back to them fast, and they start back up where they left off. It's kind of like the old task switching that predates true multitasking in computers.
There are some apps that do work in the background, but you'll normally know what they are. Examples are apps that play music in the background and GPS apps that keep navigating in the background.
Congratulations on your iPad. I hope you enjoy it.
And welcome to the forum.