Can I send a file to my printer from a computer that isn't at home?

Obviously not, the Wi-Fi won’t reach there, unless you put your item on a USB stick and print it,

But go on www.dropbox.com
You can save your files on the internet, and anywhere you go, you can go on www.dropbox.com and log on into your account and access the files and print them. :)

I have a flash drive, I was just hoping I could print my stuff and have it ready by the time I get home.

You could use something like VNC. But that is a huge pain in the ass to save the two minutes it takes to print once you get home.

In theory you should be able to

Just get a DYNDNS to point to your home computer and then share your printer at home. Then you can just go to like http://mycomputer.dyndns.com/printername and connect to it.

(Note: this working depends on security of your router at home and the router / security policies of where you are printing from – it may require some tweaking or it may not work)

HP has a new “internet printer” ... Instant printer I think they call it.

Wont work for your Canon.

There’s all kinds of ways to do this. Here’s just a few from a quick Lifehacker search: http://lifehacker.com/search/print%20at%20home%20from%20anywhere/
Also search Makeuseof.com

The Dropbox method/printer cache file seems to be one of the more popular ones.