Using for loop in R to modifying an already written code

I have a code written in R to read values from satellite imagery and csv files. I need to modify my code to read values in csv files and add them or multiply them with each band of my satellite image.

This should be easy with someone for an R expert user, but preferably someone who has worked with satellite imagery. For example using multiple linear regression on satellite imagery in R. I also have an existing code (for loop to share).