can't see shared computers

I am using a Dlink wireless router with my IMac 20. There are both wireless and ethernet connections. I have made all the sharing configurations on the other computers and I can't see them with my Mac nor can I the others see the Mac. I tried to share my printer out from the Mac and the same problem exists. I am using the wireless with the mac. I have configured WPA personal with a 9 letter security code. I have disabled firewalls on other computers and still no positive results. How do I set up the home network so information can be shared??

What are the ip's of all the computers?

IP's are set by the DLink router

And they are,....?

Verify the IP's of all computers. First Step!

I thought I had sharing on.....but it wasn't completely setup. Everything works fine now. Thanks for help.