Filemaker has built in layout options for printing labels. If your label layout matches a known Avery label number, you can create a labels and layout and specify the avery number. If you don't, you can still create your layout by specifying the dimensions of one label. Investigate those options and see if they'll work for you. Feel free to post back to here with questions if you can't get this to work for you.
Note: for best results, make sure that you have selected the printer you plan to use to print your labels in print set up (windows) or Page setup (mac) before creating the layout.