M.M.
I am 46 and have used this only since I was 21.
Buy some gel Gynol. Take your diaphragm and squeeze out about a T. of spermicide on the inner cup of the diaphragm. spread it around thick. Then take some more and spread it around the outside rim making sure to get in the crease of the rim. Insert the diaphragm. Then you can take the applicator usually supplied with the gel and insert an applicator-full of the gel with the diaphragm in place. Do this up to 4 hours before sex. But you have to remember to insert more gel with applicator if you have sex again. Don't leave it in for more than 8 hours after you've had sex. But you can take it out, clean it and reuse. I have never had a pregnancy scare with this because I used it with natural family planning based on a 28 day cycle and knew for many years when to avoid sex if I didn't want to get pregnant just to make this even more effective. There are ovulation formulas you can use if I remember they are on pregnancy.com or one of those sites. You put in the numbers for a formula that is provided and it tells you your most fertile times.
Worked like a charm for me! Good luck.