Before you start with the Meta Data setup in GD SEO Toolbox Pro, you should configure global settings for Meta Data module. All these settings are located in the SEO Toolbox menu, Meta Data -> Settings page.
The settings panel includes global settings and title output settings, like on the image here:
There are two types of separators you need to set: the main one is used to replace meta tag %%sep%% in your meta data rules. Page tag prefix is used for the %%page%% meta tag. Set the date format, description length limit. Finally, configure the use of the page tag on the first page of the archives.
Finally, the last option should be used only for older themes or themes that have an own method for generating titles without the use of WordPress functions.