How to write a Loop within a Loop?

- Loop within a loop
o The Loop is supposed to perform the following tasks here below:
1.)Copy Product ID number from Column A in “Sheet 1”, and then loop through “.jpg” files in column A in “Sheet 2”.
Basically, the jpg files for a product ID in sheet 1 will be found in Column A of Sheet 2.
2.)There may be several images or jpg files per product. If there are lets say 2 images for product ID# 641, then the values would be copied and then pasted into columns C and D of the same row as Product ID 641.
3.)If a product has 6 pictures e.g. Product ID 830, the images would be pasted into columns C, D, E, F, G, and H of the same row as Product ID 830 (in this case row 6 of Sheet 1).
I hope this makes sense. I know how to create a basic Loop, but I have no idea how to create a Loop within a Loop. I wanted to practice this skill and have been trying for some time, but I can’t get my code to work. Any help would be greatly appreciated.
Thanks