The procedures can easily be search for on Google, but for basic steps, see below:
1. Plug router into the modem, then connect all computers to the router.. Make sure they all have an internet connection..
2. Create the EXACT same username on all computers, with the same password, and give that user administrative privileges.
3. On all computers, using the new username, change the "Workgroup" to be exactly the same.. (RIGHT click on "My Computer", choose "Properties", then click on the "Computer Name" tab. When that opens, click on the "Change" button next to "To rename this computer or join a domain". On the next window, place a dot/tick in the "Workgroup" selection and give the the workgroup a name..) Make sure both computers have the same workgroup name.
4. Make sure all computers have "File and Printer Sharing for Microsoft Networks" enabled. Open the Control Panel/Network Connections icon, then RIGHT click on the "Local Area Connection" icon, choose "Properties". When that window loads, make sure the box next to "File and Printer Sharing" has a CHECK mark in it.
5. On computer 1 which has an operational printer connected to it, share out the files, folders and printers by opening Windows Explorer, RIGHT click on the C: drive, choose "Sharing and Security", then click on the line that says: "If you understand the risk but still want to share the root...". At the next window, in the "Network Sharing and Security" section, place a CHECK mark in the "Share this folder on the network", then follow the prompts to share the drive. Click on Apply, then OK.. Perform the same thing on computer 2.. You should now be able to see and share folders and printers between computers.
Please note, sharing the entire C: drive per the instructions above is not safe.. IF you're going to share files between computers, it's best, after following the above instructions, to then share out a single folder, such as the "My Documents" folder.. Once the "My Documents" folder is correctly shared, you can then return to the C: drive and "unshare" it.. After doing so, the "My Documents" folder will remain shared but the entire C: drive will be invisible.
Once all of that is done, then simply open the "Printers and Faxes" folder, RIGHT click on the printer you want to share, click on "Sharing", then share the printer will everyone on the network. Make sure the "List in Directory" box is CHECKED so all can see it.
Hope this helps.