I have a online girlfriend in Ghana that wants to come to Canada she say's that she has to do a medical for her visa that costs $500 Canadian for malaria, HIV sexually tramitted diseases and sink diseases and her visa will cost her 300 just like to know if this is true

No, it's not true, you are being scammed. Here is a whole list of the scams that come out of Ghana. Google

Thanks it didn't seem right to me I had to make sure before I did anything

Ghana is the location of a very well known scam. If they don't want money for you from one thing, they will find another reason to get money from you.

To be brutally honest, it's best to stay away from international dating sites altogether.