Good to see you're visiting my home city!
Most shops are centred on the city centre, and the big department store ar easy to find - a huge Debanhams, even bigger M&S and so on.
However, you are probably aware that Chester has rows, that is to levels of shops on the historic rows. All the little boutique shops, some of them tiny can be found on the rows which run the whole length of Eastegate Street, Watergate Street, and Bridge Street and parts of Northgate Street.
Also, look out for the little hidden streets (well more walkways really) where further little shops can be found.
Whenever you see a shopon't forget to look up a level, and you'll see another one!! Enjoy your trip.