Add a shortcode that sums data frm Gravity Forms entries, showing the result as a value, percentage or progressbar.
You'll get a new button in the WordPress post editor (this applies to post, pages, etc.).
The shortcode wizard provides you with all available settings.
If you need help finding the right placeholder for a field, providing that you've already selected the source form, just click on [?] List fields.
This shows a popup window (you can keep it open while working with the wizard) with a list of all fields you can use and some additional data for multi value fields.