If they are both connected to the same router you can set them up so they can "see" each other and then just copy files direct from one computer to another.
If you are using Windows Vista or 7 (and I assume 8) then there is an option in Windows called Homegroup to allow you to connect your computers together.
Have a look in the Windows help for how to set up a Homegroup.
But the simplest way, as Eccles says, is to plug in a memory stick or external hard drive to your desktop PC, then copy the photos on to the memory stick or external hard drive.
When you have done this, then plug the memory stick or external hard drive into your laptop and copy the files OFF that onto your laptop.
If you have not got an external hard drive then it may be good to buy one then you can backup all your important files (like photos) so you have a spare copy in case you lose the ones on your other computer.
Always good to have spare copies of important files.