General information on public skating (schedules, fees, rues of conduct, &c) can be found here on the City Of Ottawa website.
Using information from the city of Ottawa website (here), web developer Tom Wilson has produced a handy interactive map of Ottawa rinks including the canal. Click on the screencap below to get to Tom’s map.
Rideau Skateway / Rink of Dreams
Weather permitting, the downtown portion of the Rideau Canal turns into the world’s largest skating rink totalling 7.8 km long. The Rideau Skateway is maintained by the National Capital Commission, who provide online information here. Opened in 2012, the Rink of Dreams at the Ottawa City Hall plaza is another popular public skating venue—especially at night when it lights up in many colours.
This crowdsourced site describes conditions on various rinks over the past 24 hours.
The City of Ottawa provides information on recreational skating lessons here.