How do you track your BBT?

Anissa • one gorgous doll baby in 2015 😍 one miscarriage at 7 weeks March 2018 😔TTC baby #2! 🌈

Ok, just stayed trying to keep up work my BBT, but how the heck do I track it on here? ???

I also took my temp yesterday and it was 98.1. Today it was 97.4, how are they do different? AF has shown for me so I know it's not signaling anything. Any pointers one how to get an accurate temp?