On the data create page, you choose what data you want to pull on the activists targeted by your universe in the first step. Each data field you select will become a column in your spreadsheet.
Choose from the drop down menus any of the fields available -- you can choose the built in fields (first name, last name, email, zip/postal code, address, city, full state name, state abbreviation, country, legislative district, OCDID, our internal identifier for legislative districts, and county) or choose from any custom fields you've created on your pages. If you need more columns, click the "Add More Fields" button to add another drop down menu.
You can also choose to include a column for "Subscription Status," which will be either "subscribed", "unsubscribed", "bouncing", or "spam complaint" depending on whether that activist is subscribed to that list or has a bouncing or spam complaint email, "Subscription Update Time," which will give you a timestamp of when the subscription status was last updated, and "Subscription Detail" which will give you the bounce message, if any.
You can include a "Tags" column as well, which will output all tags for each activist.
And, if you have chosen one and only one action in the action history targeting include section, you can select columns for the referrer, source code, and timestamp of when that activist took the selected action.
Note that custom fields you create won't show up in the drop down list until at least one activist has filled out that custom input. So if you just created a tell your story form with the "story" custom input, "story" won't show up in the drop down list until at least one activists enters something in the "story" box and submits the form.
When you're ready to get your results, click "Save & Get Results" to move on.