The "Create Event Wizard" will guide you through the setting up of a new event file. The "wizard" is shown when you use the menu item File / New Event File.
This page is shown when you have selected to use one map file. It has a "select file" button that you need to use to select the map file to be used.
Condes will store the file name of the map file so that the next time you open this event file in Condes, the program will know where to find the map file. If you move the map file (or open the event file on a different computer), so that Condes cannot find the map file, the next time you open the event file, you will be asked to help Condes locate the file.
This is also where you can enter the printout scale(s) to be used.
The selection on this page affects the map and control settings for Canvas 1, and possibly Canvas 2 (if two printout scales are chosen). You can later change the settings by using this dialog: Canvas / Map - Setup Map dialog