InfoPath Dev

I am new to InfoPath and Sharepoint. I have built a form that is a Sales Report and Time Reporting combined for our sales team. The form contains individual repeating sections for new customers, exisitng customer and customers that buy in mulitple areas. What is need to do is calculate the # of customers input into each section to provide a count of ,for example, how many new customers signed contracts. I can get a count of the number of rows presented in the repeating section but I need it to count only the rows that are populated with information. I've tried conditional formatting and rules to try and have the default value of a separate count field set to 0 unless it is populated but I can't get it to work.  I can easily get it to count every row, populated or not, Any ideas on how a can produce a field in a repeating section that counts the populated rows.

Look into using filters.

When selecting the records to count use the filter button in the lower left to set a filter [customer = 1]  you may need to look at the preceding sibling function to count unique customers, etc.  It will be a bit complex but can be done.

Search here on preceding or sibling for more examples.

Where do I see the filter option?

When selecting a field in Formula Builder there will be a button in the lower left of the window.

I'm completely lost. Do I set this filter when I'm building the form, creating a view or where? I don't see anything call Formula Builder.