I have an old (1972) Bernina 830 Record, and have at least tried all of the feet at one time or another. If I don't use one for a long time it's not unusual for me to forget what it's for. So to try to prevent having to scour the manual, I sort them in baggies in a box with alphabetically ordered dividers and put a piece of paper in with each one telling what it is and the page number in the manual where it's explained. This has helped me a lot, to the extent that I remember to put them back correctly when I take them off the machine. If your machine is from that era I can probably identify the feet, but it may take some doing because my machine and its parts haven't been unpacked since our move last year. The business end of the feet will be similar to those of many other machines and shouldn't be too hard to identify. Here's a web resource that may be a help, depending on which machine you have - scroll down to where she lists the answers.
http://mimikirchner.com/blog/archive...ew-tools-toys/
After you know what foot you have, it's often possible to go to Youtube and find a video demo of how to use each one.