Use the goggle search engine and there are quite a few hits. I found one site with a manual for $l0.00 and another which offered free download of threading instructions, bobbin filling etc. Just do a search and I'm sure you will come across something that will work for you. Good luck. Budster - sorry didn't make note of any addy but there are lots!

If it is a 700 series from the 70's it uses a specific bobbin and you fill it in the drop in spot. There should be a little button what shows a winding red circle inside the bobbin case area and you press it to the left. Once filled it will move back in place when shutting the plate.
Susan

Manual at below site $10.00 charge.

http://www.sewusa.com/Sewing_Machine_Manuals/Singer_Sewing_Machine.htm