Help! I'm new at this & don't know how to use the chart properly

Hello! Is there anyone out there with instructions or a manual on how to use the chart & what information I need to enter on the chart. Also what is the BBT - is it different to when you take your temperature the normal way or is it the same.  We are trying for baby number 2 & I would like to get it right.  If anyone can give me a push in the right direction, it would be much appreciated