Need help with calculation

     Each order would have  a status field. Paid / Unpaid.   You also have a summary field of your order totals.  Create a globle field of the type of orders you want to view Paid / Unpaid, and set a relationship between this field and the status field.  Display your summary field based on this relationship and total would show paid / unpaid which ever you have your status field set too.   You could have 2 global field to show both totals at same time if need.  Also your Global field could be a popup menu to select paid/unpaid.

     This is about as simple as it gets.  The best way to learn is to put into practice.  There are a lot of great books about filemaker online and filemaker come with starter solutions that you can view and learn from. 

     There are multiple ways to do this.

     The simplest to explain is to add 4 fields (plus the status field that shows paid or unpaid) to your table.

     Define a field, cPaidAmount, of type calculation:

     If ( status = "Paid" ; Amount )

     This field will be empty if status is unpaid.

     Define cUnpaidAmount as:

     If ( Status = "UnPaid" ; Amount )

     Then define to summary fields, sTotalPaid and sTotalUnpaid to compute your two totals.

     Define sTotalPaid as a summary field that computes the total of cPaidAmount. Define sTotalUnpaid to compute the total of cUnpaidAmount.

     These summary fields will compute totals over all records in your found set. Perform a find for just a certain group of records, such as all records for the Month of April, 2013 and these fields will compute just the totals for that month.

     I gave you exact insturctions.  Phil gave you a different method.  Both gets the results, I perfer the method I gave you.  My insturctions are simple, you just have to want to use them.   Setting up a global field or create a relationship as metion above is simpe as it get in filemaker.  Sorry I tried to help.