BBT? How To?

Can anyone walk me thru it. I've never tried this method and would like to try to conceive this way as I think depo has completely messed my body up. Always had 7 day flow til pregnant with 1st child then got on depo after her birth. And no period for 1yr and half on depo. Got first period first of September ending 5th. Now back flowing the 29th. So I need a how to on the bbt method. (Like a blonde version cause seriously never knew I could do it this way)