It all depends on what operating system you are running. This goes for mostly all the OS from 98 to XP.
To share files, you just need to create a folder anywhere on your desktop and give it a name. Then you right click it and go to "Sharing" or "Sharing and Security". You just ask it to share and make sure you click on the "Allow other users to make changes" so that you can change the files on that folder from your laptop computer.
You can do the same for the printer. Go to Control Panel, Printers and right click on the printer you are trying to share and ask it to "Share".
Then you go to the laptop and open up "My Computer" type in the desktops ip address as such (192.168.1.101) and this will open the desktop computer if you have any folders or files that are set to share. Make sure your firewalls are turned off for both your OS and your antivirus. You will then see the printer on there. You just need to double click the printer and if it asks you to download the drivers from the internet just say "yes" or "ok". You should also be able to access the folder you set to share on your desktop and should be able to make changes. I have set up these types of networking for many businesses and homes so they definately work. If not just send me a personal e-mail and I will be happy to assist you.