How do I make my hp J4580 printer print wirelessly from my mac 10.7.5 laptop

Hi,

I would like to make my HP J4580 all in one printer wirless.  I have a mac 10.7.5 laptop.  I have read the other posts and it appears to be possible but I can't figure out how to do it.  One of the posts said you need an Ethernet cable, however, there is no place on the back of the J4580 printer to hook up an Ethernet cable.  I tried hooking up the USB cable that came with my printer to my new comcast modem that has wireless, however, that did not work.  I do have sharing on.  

1.  Is it possible?

2.  If so, how exactly is it done?  Since I'm not that computer savvy, I do need step by step directions.

I copied this from one of your other posts.  The back of my computer is exactly the same.

Thank you,

HR