The icon in your post says that your browser user agent
reported that you are using Ubuntu. (Gosh, looking back, that is a horrible bunch of geek-talk in one sentence.)
You probably need to enter a terminal and use sudo. It will ask for your password.
More about sudo and Ubuntu here. If you're going to use Ubuntu, you need to learn about sudo:
It is possible to start a graphical program from the command line. For example, sudo gedit
in a terminal starts the Gnome text editor with root privileges, so that it can be used to edit configuration files.