Bob-Dubery
You don't say where you are, which makes recommendations for a specific shop difficult.
You do need to get the right strings for the guitar. Putting nylon strings on a guitar built for steel strings will result in a not very impressive sound. Putting steel strings on a guitar built for nylons may result in significant damage being done.
Take the guitar to a local musical instrument store and ask their advice.
Is your boyfriend an experienced player or a novice? If the former then he can probably tell you what strings (brand, compound, gauge etc) he prefers.
