I use persona so not exactly the same, but I think you just pee on them for about 3 secs first thing in the morning. If there's one line they're working but you're not ovulating at the moment, if there's two lines you're about to or have just ovulated. You should ovulate 10 to 12 days before you AF, so use them around that time if your cycles are regular and you know when that is likely to be.
Hope that helped a little but do check the label of whatever you're using.