Click on 'Opera' lo-go Top LHHC >Bookmarks>Manage bookmarks>New tab/window opens click on 'File' then choose what you want.
Good luck.
I also set up some of the properties of the browser --- Click on 'Opera' lo-go Top LHHC >Settings>Preferences>new window opens up, there are a lot of things you can set, ask if you need help.
On this PC I have 6 different browsers set up with lots of 'Tabs' and then I can use them for, say, one for looking for Holidays another for Technical things another for looking at my London trip etc.