There are several ways to track your cycle. The cheapest being checking your CM, then BBT (basal body temp) and then OPK's.
If you go with BBT, you need a special thermometer (you can get them at WalMart for $8). You need to take your temp at the same time everymorning. Right when you wake up. No getting up, no talking, no drinking water, nothing. As soon as your eyes open you should pop the thermometer in your mouth :) The one I have has memory, so you don't have to record the temp just then. Then you would plug your temps into an O Tracker. Then interpreting the temps gets complicated from there. The most important thing to remember when tracking your temp, is that it will only tell you AFTER you have O'd, not before.
The book Taking Charge of Your Fertility is a wonderful resource and details all of the tracking methods.
I was checking my temperature every morning and keeping an eye on my CM and noting the changes in it. I also kept record of it all on fertilityfriend.com.