The A1 is for the District (Boston), the G1 is the plate position on the sheet, and the G2 is the Face Plate number.......FW designates the note was printed at the Fort Worth facility. You can read more about it here; http://www.uspapermoney.info/general/note.html
If you're asking if you should keep it, my opinion is no. The note is in bad shape and is unremarkable. Spend it.