I found temping super helpful the first time around. Now that I'm older and have more disruptions in my sleep (child waking up, cats waking me up, etc.), it's not as reliable as it should be.
When I was TTC my DD I knew I was pregnant before the tests detected it because of my chart. You start temping on CD 1 and try for the same time every day. Use something like Fertility Friend to track it. Makes it easy, you just input the temp and the time you took it.
You need to have 3-4 continuous hours of sleep to get an accurate reading. If you happen to wake up at a different time, you can still input it. There are also BBT adjusters that will tell you what your BBT would have been if you had woken up and temped at the right time.
They will be all over the place pre-O and you will get a "baseline" temperature. When you O you will get a temperature spike above baseline and as long as it stays there, I think for 2 days or more, the first day it spiked is considered O day. Temping isn't for predicting O, but it confirms that you did O. If used in conjunction with opks, it can help.
After you O, your temps should stay above your baseline and if you conceive, they will remain high (although small dips are normal). If you don't, you will get a sever drop towards or below baseline. I always knew the day I got a big dip I would start AF.
So that's it in a nutshell lol I was way more in tuned with myself and temping with I was TTC #1 - now I'm just doing it but not relying on it all that much.