How can you follow your temperature to know when ovulation is occurring?

Check in the AM. Check your temperature every morning before getting out of bed. Look for a temperature drop, usually around d12-13, and then a half degree temperature rise, day 15-16.
Basal body temp char. Buy at walmart a basal body thermometer and chart your temperature from the day you start one period until the next. Google a basal body temperature chart and put the information on there, that's how to do it.