I didn't know how to measure with a Laser measuring tool when I first got this inexpensive Surgoal tool. Watch this to get a quick understanding of how it works. I'm using the SG Surgoal Elite R-100, but it seems that the basic principle and functions are similar on other laser measuring tools.
Check out the model in this video with with my paid Amazon affiliate link below (Thank you if you decide to purchase!).
amzn.to/4d9abvl Laser Measure with 2 Bubble Levels 328ft Outdoor Digital Laser Measurement Tool