Can someone please advise in layman terms how to change the background colour of a section within an email template? Thanks.
Do you mean inside a repeating element? It's not possible to have a repeater with alternating colours at this time unfortunately. If you mean more generally how to change colours, you might want to run through some basic HTML/CSS tutorials for that kind of info.
See http://htmldog.com for example.
Normally you would do
or something similar.