Go to the official website of Opera, and select a distribution appropriate for your operating system. You can choose two ways to install: with the preservation of the program on the hard disk and without it. It is better to choose the first way, however when installing from the hard drive you will need a network connection.
When the download finishes, run the downloaded installer by double-clicking. Don't forget that the Internet should remain connected. The program will install the browser without any manual intervention. At the end of the installation the installer will check your system configuration, you will find that the computer has other browsers, one of which may already be installed by default, and will instantly display the window with notification. To "Identify as Opera app by default for viewing web pages?" answer Yes by pressing the Yes button.
In this case, the browser will be immediately configured with the settings at default. But how to install unknown app, not testing its capabilities in business? Of course, if Opera is already installed, but you only get acquainted with its features, then by default you have most likely configured a different browser. But you appreciated the advantages of Opera and decided to use it as your primary program for viewing web pages. Then in the settings of the program will have to make small changes.
Run the browser in any convenient way for you. In the main program menu select "Tools" - "General settings". Opens the main settings window of the application with multiple tabs. Also call up this window by using Ctrl+F12. Go to the last tab – Advanced.
In the left part of the window, select the command group "Programs". In the center, below the text box will be a checkbox next to the inscription "to Verify that Mozilla – browser by default". Check this checkbox and click "Settings" to the right of the label. In the opened settings window, you can click "Select all" or specify other parameters at its discretion.
Close this window by clicking OK and confirm the changes in the General settings window, also click OK. Restart the browser. You will find that your changes did not take effect and the program again prompts you to install the Opera browser by default. Confirm your decision to designate it as such by clicking "Yes" in the query window. Make sure that the browser is assigned by default – open any folder with web documents and you will see their icons changed to the icon of shortcut Mozilla. In addition, in the "Settings" on the "Advanced" tab, you will see that you selected in the previous step become available.