S.R.
They work...the package should explain exactly how to use it. I don't remember all the details of the procedure, but I used one to conceive my son 11 years ago and what I remember is keeping a chart of my cycle, and then peeing on a lot of little sticks until I got two pink marks, which meant I was ovulating. (I remember calling my husband and telling him that "there were two pink lines," and that we had to "get down to business" ASAP, lol!!!) I had to use one because I have PCOS and had to take Clomid to ovulate at all, so I needed to know if the medication had any effect. The ovulation predictor definitely worked accurately, because I have a nearly 11 year old son to prove it! :)
Good luck to you -- I hope that you have a "positive" outcome (in more ways than one)! :)
S.