I am in Canada. I would like to be able to connect to the text
messaging services of mainland China. I would like to be able to send
and receive SMS messages.

I expect that there are a few possibilities:
- choosing the right Canidian mobile services provider
- using a service on the web
- adding a service to the Canadian mobile servies provider that I
eventually subscrive to.

Please advise.

I'm not sure if this is what you want but www.teleflip.com will send
text messages to any text enabled phone in North America(the people
sending you messages could use this).A google search for"free SMS"will
give you several companies with broader coverage,here's one for China
http://sms.asiadragons.com/china/