Yep, you wee on sticks on the days it tells you, then insert them into the monitor. From what I remember (google this as I may have misremembered), for the first month you may have to use 20 or so, but once it 'learns' your cycle it may only be about ten per month. It measures the hormone levels in your wee so it can predict when you are about to ovulate, and then indicates the three days when you are most fertile. The instructions are clear and I found it easy to use. It just takes the guess work out of the whole thing, so you can focus your DTD efforts on a few days per month rather than trying to do it ALL the frickin' time
Just a thought, have you had some blood tests at the GP to check your hormone levels? After 12 months they are usually happy to do some basic checks on you and your DP just in case you need a bit of help. I had them and they came back fine, but it was reassuring all the same.