Open up Impulse.  On the top bar there should be a tab called Updates.  Go there, and update as necessary.  Also, right clicking the game in the your games list inside Impulse should give you the option as well.

I assume I am now on .23 but how can I tell?

If you have the Impulse tray app running, it's supposed to tell you when there are updates, but the option to do it for beta software seems to be off by default. Right click on it, go to settings, and enable that.

Next time there's an update, it should tell you.