Click the EXPLORE button in the bottom tab to open the explore window.
There are three categories for regions; 'Featured', 'Popular' and 'Friends'. The Featured list shows mostly Sinespace owned regions, but it does show some of the most popular creator regions as well. Popular is where you will find the most visited regions, and Friends will show all of your friends' homes and regions.
To enter one of these regions, click on the 'Enter' button next to the region image. To get back to the Welcome Center, you can click on 'Explore' again, find the Welcome Center and click on 'enter'. If you are wanting to find and visit a specific region, you can use the 'search bar' above the Featured, Popular and Friends tabs.
You can also see a list of each of your friend's active regions by clicking the HOME button in their PROFILE.
Or by clicking EXPLORE (bottom menu) and then clicking the FRIENDS tab.
You can click the minimap in the top right to bring up a panel showing information about the region you are in.
This includes the region url, so you can share a direct link to the region with anyone. And embed code allowing you to embed a portal to the region in a website, blog post or facebook post. Note: This is for web viewing, some regions are not able to be viewed via the web.
If you own the region you can also set access permissions here, limiting who can enter the region and who can spawn items.