I believe the easiest way to do it would be through Fiji. There you can select your ROIs in all the frames and get a measure of the fluorescence intensity for each ROI in each frame. Watch this video tutorial as a starting point:
https://www.youtube.com/watch?v=ENeCE_iur_o.
By the way, I don't know which software you used to acquire the image, but some of them have their own tools to perform this kind of analysis.
So, it is cellSens that you're using, am I correct? If so, check this tutorial, it may be helpful:
https://www.youtube.com/watch?v=CuZZRB1yegI
Also, keep in mind that if you're using it for your analysis, the software can be purchased in different packages (from the simplest to a full version). Know which package you have so you'll have access (or not) to all its functionalities.