There was a loose pickguard inside the gear compartment of my new guitar's hardshell case. I assume it's for the guitar but I'm unclear about how to attach it. Why didn't you do that before delivery?
Many guitarists prefer a guitar without a pickguard so we feel it makes more sense to give users the option of attaching one or leaving their guitar as it is.
We do ship pickguards with every guitar though. They're very easy to attach. Remove the paper backing, Lightly position the pickguard under the sound hole so it sits just below the rosette. Rotate it so the top edge is approx horizontal (or parallel to the strings) and press it in place. If you have a clear pickguard the backing material is actually a thin sheet of clear film rather than paper but the procedure is the same - with one small caveat: The pickguard should be pressed into place working out from the centre making sure that no is trapped. Any air pockets will be visible.
If you choose to attach a pickguard please do so after you've used your 7 day "Love it or Leave it" trial period to make sure the guitar you ordered is right for you. Once you modify the guitar it no longer qualifies as being in the same condition as when it left our loft.