Printing Banners?

[Phelptwan]

So last week my department was given a "broken" HP 120nr, turns out the network card was just fried. My boss wants to use it to print banners. So I guess i'm just looking for some general information on printing banners, such as size specification (A1, A2, A3, etc.), applications that make it easier to print banners, anything like that. So far I can't get it to print more than an 18" long sheet. Which is annoying since it's 24" wide paper.