Use a Windows "Briefcase".
Create a new "Briefcase" in the laptop and, while the two PCs are connected, drag the folder containing your website files from the Desktop PC into the Briefcase in the laptop. Probably best to *right* click to drag & drop and then select the option to "create sync copy here".
You can then update files in either the Desktop or the Laptop (loading and saving the file directly from the Briefcase) and when the two are networked again, use the option to update the Briefcase. Don't change the *same* file in both PCs between synchronisations because it works by replacing the older file, in whichever PC, with the newer one.