Firstly, go to gotomeeting.com and log in - you have the credentials (I don't have them, but they are saved on my computer) Download GoToWebinar.

Once that is opened, click on "My webinars"

Select the pre-scheduled webinar regarding landlording.

Start button is in the upper right hand of the screen.

You'll be prompted to launch something. Open.

Pay careful attention to the portal on the right. You want to share screen, select audio options (phone), select web cam (optional) and so forth. 

Pull up your PowerPoint slides, in full screen and have at it.