i have one coputer at home and my boys want to play with. how can all three of us play at same time weather its single player or multi player or i create a game just for us? thanks :-) lol

I know you can log in with two accounts at the same time in Firefox and Chrome respectively, maybe a third browser could allow for a third account.

you have to use three different browsers.
On my computer i once had three accounts online, with Safari, Chrome and Firefox.

Another option would be to play from your phone, while the second person uses the pc. Although the mobile version is, in my opinion, not as good and useful as the desktop version (due to limited options, a menu that isn't as easy to browse, less overview due to having to zoom in quicker etc) it can be used to play casual games. In this case I dont think you guys are going to play highly competitive games, so using the warlight app might be useful.

Edited 9/24/2016 22:00:49

Multiple browsers or same browser with incognito modes

If you make your games multi-day, rather than real-time, then you will not have so much time-pressure to finish your turns. Therefore, you can each play your turns sequentially, rather than simultaneously, which is kinda-sorta (not quite) the way the original Risk is played. Therefore, you could use the same computer, and just take turns.

This would take longer, but might be more fun, less pressure and stress. You could probably play a game over the course of a few hours (or less, it all depends on the map, etc.) this way. You might be able to get away with using three different browser windows, so you don't have to log-out/log-in all the time, but worse comes to worst, you could manage with a single browser window.

Although it would technically be a 'multi-day' game, there's no reason you have to spread it out over multiple days. You can finish your turns as fast as you want.

or like incognito mode.

Other thing, you can't play together single player, but you can play together against AIs, just create a multiplayer game with AIs instead of open seats and invite the other accounts.