After I call an interrupt, where does the code go from there? Does it go back to the point in the code where the interrupt was called? Or does it go back to the start of the main loop?
-TC
After I call an interrupt, where does the code go from there?
You don't call an interrupt. An event occurs that triggers an interrupt - either internal, such as a timer ticking, or external, like serial data arriving.
Does it go back to the point in the code where the interrupt was called?
Yes.
Or does it go back to the start of the main loop?
No.