Image processing in MATLAB or any other software....need a starter for my project..

We are basically trying to find out the time interval between the instants that a particle is in a particular initial point and that at which it is at a particular final point...

i have a video in which the particle in question is shown to travel between these points...but obviously, these regions are not marked out on the video, since these are just hypothetical.

The idea is to make a code on a software such as MATLAB that we can use during experiments on the particle we are investigating so that each time we do the experiment, we can be sure as to how long it takes to do so.

Being new to programming, I have no idea how to begin this..I need a starter...I thought
of using MATLAB image processing...I don't know if that's a good idea....

Could someone please tell me how to start? How do I make a code for this??? What do I need to know? What extra stuff do I need to study?