Xojo report.Run

i’m trying to figure out how Xojo Report works but even with the examples i have some difficulties.
I’ve used the Products example in xojo folder as base and modified the report layout a little then i’ve run a query on a mysql db and i would like to show the recordset i got from the query in the report but i can’t understand how to link the recordset fields to the report fields.
In the example there is this row :
ReportPreviewContainer1.ShowReport(rpt, rs)

but where is defined which field in the rs is linked to each field in the rpt ?