1.) Download Sophos Central, be sure to select "SophosInstall-PC.exe"
2.) Go to your Downloads Folder and launch SophosInstall-PC
3.) If a Security window pops up, click Run
4.) When Sophos launches, click Next
5.) Wait for it to run its checks
6.) When it's done, click Install
7.) This step may take a few minutes, so please be patient.
8.) If you are prompted to restart your computer, check the box that says Restart now, then click Finish
9.) After you've restarted your computer, you are all set.