I’m going to assume based on your description that you’re using a combo dsl modem+router, and that the PC is connected by wire to a LAN port on the router, and the laptop is using wireless to that same router.
It doesn't matter whether your devices are wired or wireless, if they're successfully connected to the router, they can communicate w/ one another. However, there can be non-network related issues that prevent access between devices (e.g., OS level security).
If you want to “sync” the PC and laptop, you need to use appropriate software (e.g., SyncToy, Second Copy, Robocopy). And of course make the folders/file available between the two devices using Windows file/printer sharing (that’s where the security aspects come into play). If you want to make the external HD available to the laptop as well, here again you would need to share that device using Windows file/printer sharing.
Thank you for your quick response...You're correct in your assumptions as to my connections. I will investigate the software you recommend and see what I can do with the file sharing security aspects.