what do I do?

I have a question…
I want to run a forum about car modifications to allow members to register and post questions..
so I came up with a domain name, this is just an example; Exampleforum.ca
after doing more research I noticed there is a forum already created at Exampleforum.com
If I register Exampleforum.ca and offered the same experience as the already running Exampleforum.com site would that put me at risk of legal issues with Exampleforum.com they do not have any registered…

what do I do?