To pin tabs, right click on the tab you would like to pin then click on "pin tab". After you've pined more than one tab, you can drag them to the order you would like them. Close your browser, then open it again and the pinned tabs will appear again.
Note that if you open another browser window in addition to the window you have the pinned tabs in, the browser window that is closed last will be the one that opens up next. Be sure to close the window with the pinned tabs last if you want them to appear the next time you open your browser.
