It is good practice to keep each slide under 200K in size.  Some participants may have slower Internet Service Providers.  The smaller the size, the faster the image is resolved and cached on a participant's computer.  

An easy way to make PNG slides, is to use PowerPoint.  On the "save as" menu, there is a choice in the "save as type" drop down menu. Choose PNG from this menu, and a directory will be made with all your slides in the format you have chosen.  Upload the contents of that directory into the Content Manager so the slides have URLs attached to them.  Copy and paste the URL into the text message box to post the slide into the LBD Environment.

If you need more room in your account in the content manager for presentations with many slides, send an email to mike@learningbydoing.net with the name of your account.