You probably check your statistics all the time for traffic right?
Well when someone comes to your website and you see they came from another website, do you ever check the website they came from?
Getting any ideas?
If you don't get it. If you place a link to someones website on your site or just click on their link on another website/page, etc. They could then in turn check out your website.
Here's another tip.
Imagine you already have good traffic, but you want to create relations with another site/page/channel. A good way to do this is by directing your traffic to their site/page/channel. If you do that, they could in turn be very grateful and return the favor
P.S. These methods are tried and tested and they work. It's just another way of building traffic indirectly.