IN FTM 2012, you (1) select "Export" under the File menu, then (2) select "GEDCOM 5.5" under "Output Format", select the people you want to include, and check which data you want to include, then (3) select "Other" for "Destination" (UTF-8 should be automatically selected for the Character Set), and (4) name the output file (with a "ged" extension) and save. Should be similar in earlier versions of FTM.