Hum, go to FIDO.ca and look for a link on its front page after you select a langauge, or simply try again.
I think every carrier has their own web based text message service that's free to use to send. However, most carrier will charge a fee on the recieving end, unless you are sending cell to cell.
I am sure there are other web sites that will allow you to send text messages to cell regardless what carrier the message goes to. I don't know one that will do it for all Canadian carriers, most of these services are only for US.
Hope this doesn't complicate things.