Surf is basically a standalone web view with a very limited feature set, and as such has no tab support. From the web page you linked:
I'd never thought I'd enjoy using a browser with no tab support until I forced myself to use surf for a week.
Everything else is listed in its
man page, with is part of the download and installed with the browser.
man surf will help if you installed it properly. You can also open the almost plain-text file
Ctrl-H goes back,
Ctrl-L forward. There are additional shortcuts for incremental searching, scrolling, printing, reloading and a handful of other things, but that's it. Notably absent, of course, are shortcuts for handling multiple tabs.