Its different from brand to brand.
Page 7 in your manual will tell you the procedure, which also has pictures to help.
I hope you bought the DX7s with the transmitter and AR8000 receiver. RTF RC vehicles many times come w/o a receiver as they are not universal but only work with particular transmitters.
For your safety remove the props when doing this, and mark them so you know which prop goes on which arm.
Since your question was a basic RC question I would highly recommend that you read the wiki manual to familiarize yourself with the features and vehicle before you start trying to fly. If you don't you may end up with your new drone flying away never to be seen again.
This hobby is great, but just because you bought something ready to fly doesn't mean you are ready to fly it. Take your time - relax and learn about each new function you use before you use it and don't do too many new things at once. And don't get complacent! =) Many of us have even put together rudimentary pre-flight check lists.
(I have 450$ worth of foam plane I got complacent with in a pile in the basement waiting for me to patcher up.)
Many of us took many months of getting to know the vehicle and how to tune and fly it before ever trying RTL or Auto missions.
You didn't buy a toy - you bought a fully autonomous robot that you are asking to do things, take the time to understand the rules and you won't regret it.