Problem with coding for PIR sensor to lcd display

hi, I'm currently doing a project of a PIR sensor connected to a lcd display with an Arduino. I would like to calculate the time difference between 2 hits of the sensor. So basically, when i hit the sensor once, it will start calculating the time, when i hit the second time, it will stop then save the data. Then it will start counting again after the second hit and calculating the time again. It continuously calculates the time before I reset it. The maximum time before the reset will be recorded on the lcd display. Please help me with the code. I seriously need help. Thanks guys ;)))))

We can’t see your code.
We don’t know what your sensors are, or any other design constraints.

See our problem?

Sorry I'm new to this ;( I am using a HC-SR501 PIR motion sensor and LCD1602 Display. I am a beginner so i haven't started my coding yet. I have been researching about the codes like I know how to simply set up everything and connect them together but i have 0% knowledge of how to code. That's why I am seeking for help here ;((((( please help thx

If you open up the IDE, click on “File” you’ll see loads of worked examples.