Hi Clarissabell, I'm so glad you're pleased with the findings, it makes it all worth while. In answer to your question, "how did you do it", with a lot of help from Ancestry

and not giving up when you think you can't find something.
I think the place of birth of Toronto for Florence Howson on her marriage record is incorrect, she is on the 1871 Canada census as born England. This means the family most likely did emigrate in 1871.
Here they are in 1871 living in District 46 West Toronto.
Elizabeth Howson, widowed, b. abt. 1833 England
Annie Howson, b. abt. 1857 England
Harris (must be Harry) Howson, b. abt. 1859 England
Florence Howson, b. abt. 1864 ENGLAND
Eliza Howarth, widowed, b. abt. 1798 England (not Elizabeth's mother, she is Sarah. How is Eliza related?)
Elizabeth is listed as widowed, so sadly it seems James Gilbert Howson must have died very shortly after they arrived in Canada, if the 1871 immigration is correct. I'll see if I can find a death record.