Assuming both computers are using the router....
You need to create a share, say on the desktop (right click on the folder you want to share select sharing, then you can either click the share wizard for network or just select 'i understand about sharing just share it' . Give it a share name.
Then from laptop (i assume vista does this the same as XP) You need to select map network drive (from my computer....tools) then enter the path of the share.....ie it needs to be in format
\\deskt"My Naff Code Reader"putername\sharename
Job done

I assume the printer is connected to the desktop......if so you need to share the printer too
Then on the laptop select add printer and select add printer connected to another computer (again assuming vista does this in the same way as XP)
Next.....
I assume you have encryption enabled on the router.....theres different types of encryption.....WEP is not really recommended......to easy to 'crack' ........you should have a passkey set on the router.....and the first time you connected your laptop to the router it would have wanted the passkey.....once entered correctly on the laptop it wont ask for it again

HTH