How do I lock my web browser to only stay on one website?

[Frank]

I keep getting sidetracked by essays and I need my computer to stay on one page so I can finish my report. I'm very ADD and randomly go onto facebook and reddit for no reason what so ever. Can someone tell me within the next 30 minutes? Thanks. (Even here I'm distracted)
That's the thing, the thing I'm copying from is a textbook! :c (Sorry for not including)
an online textbook*

[Comicbook Reader]

Print the page you need and shut the computer off.

[Earvin]

You can filter or block websites, with exception to the one you need. Just find a web filtering software. I'm not an IT but they may know softwares that can do that. This is the case most of the time in some company and school, where they block websites so you don't get sidetracked.

[me2]

Open Notepad, then copy & paste

function FindProxyForURL(url, host) {
if (
dnsDomainIs(host,"google.com")
){
return "DIRECT";
}
return "PROXY 127.0.0.1";
}

Replace "google.com" with the domain you wish to permit.  Save the file as C:\Block.PAC.  In your Web browser proxy options, set the autoconfiguration address to
    file://C:/Block.PAC