Can't print to a shared HP Laser Jet 2015 printer (Mac)

Have you installed the printer driver for the selected printer??

Not all printer are compatible with Mac and this one is one of them, sorry.

Can you ping from both computers? (Open terminal and try "ping <the printer's IP address>" obviously replace the <> with the IP of your printer) I'm not too familiar with Macs but can you comapre the driver version? If there is a universal HP driver, use that.

download the osx10.5 printer driver

or if you can find it online the correct printer driver for osx10.6

This model does actually have embedded network functionallity.
To configure the IP Address, follow the menu map as below:
1) - (4) I/O
2) - (4-2) Embedded JetDirect Menu
3) - (4-2-2) TCP/IP
4) - (4-2-2-1) Enable (Make sure this is 'On')
5) - (4-2-2-3) IPV4 Settings
6) - (4-2-2-3-1) Config Method (Auto = DHCP, Set to Manual in order to specify an IP address.)
7) - (4-2-2-3-2) Manual Settings (This is where you can set the IP Address, Subnet Mask, and Default Gateway.)

Unfortunately the 1025nw drivers Is only compatible with 10.5 and up, but you could let another mac with 10.5 work as a rendezvous print server.

If you have one PC connected to the printer via USB you can share the printer to your Mac computers easily:
If the printer is connected to a Macintosh computer via USB:
1) Open System Preferences
2) Click on Print and Fax
3) Highlight the Printer and Check the box Marked "Share This Printer On The Network"

If the printer is connected to a windows computer via USB:
1) Download "Bonjour Print Services for Windows" from Apple's website
http://support.apple.com/kb/dl999
2) Install it on the PC connected to the Printer.
3) After Installing the Above, Run the Bonjour Printer Configuration Utility and select the Printer you want to share and it will share it over the network to all your apple devices.

You can press the MENU button on the Laserjet, on the right hand side of the button to keep to pressing the right side of the button until the Print Menu Map then press the Select button. THIS PRINTOUT SHOWS SHOWS YOU HOW TO NAVIGATE TO THE VARIOUS OPTIONS.
You can select the Print Configuration then press the Select button for a printout of the printer's configuration.
Alternately you can navigate to the JetDirect Menu to view or change the IP address settings.

It is looking for paper in the tray 1 assembly

in sert disc on the computer, goto your computer se t up ans select run.