Hi An8willbegreat, welcome to Thunder’s Place!
How to measure (taken from the instructions on the PE Data Page):
Erect Length: Either standing up or lying flat, hold your fully erect penis perpendicular to your body. Take the "0" end of your ruler and press it against your pubic bone, along either side of your penis. This is your bone-pressed erect length measurement. Use the same ruler each time for consistency.
Erect Girth: Measure at midshaft. You may either use a tape measure or a string (which you would mark and compare against a ruler to get a measurement).
Flaccid Length: Measure it as it hangs, NOT bone pressed.
Flaccid Girth: Same as for erect girth.
LOT stands for Loss Of Tugback and is used to help you decide the most effective way to PE. Read the LOT theory thread at the top of the main member forum to find out more. For visual help in determining your LOT, check out the diagrams in these posts by SS4Jelq and helluvastud.
BTW, in case you don’t want to wait for an answer, you can always use the search function. It’s great for finding answers to questions such as these. Check out TT’s Tech Tips For Thunder’s Place for tips on effectively using the search feature.
Enjoy your time here at Thunder’s Place and good luck with PE!