Opera offers you the choice to display its Speed Dial interface or restore your previous browsing session, among other options, each time the application starts up.
Click on Opera's Menu button, located in the upper left-hand corner of the browser window. When the drop-down menu appears, click on Settings. You can also utilize the following keyboard shortcut instead of selecting this menu option: ALT+P.
Opera's Settings interface should now be displayed in a new tab. Click on Basic in the left menu pane, if it is not already selected.
Locate the On startup section, found at the top of the page and containing the following three options accompanied by radio buttons.
Open the start page: Display's Opera's start page upon launch, containing your Speed Dial pages as well as buttons which link to Bookmarks, news, browsing history, and more.
Continue where I left off: The default selection, this setting instructs Opera to load all Web pages which were open at the end of your last browsing session.
Open a specific page or set of pages: Renders user-defined page(s) each time Opera is opened, configurable by clicking on the accompanying Set pages link and entering one or more Web addresse