Hi Anita,
I applied for my own visa the last time I went to Canada in 2018. You can apply for an Electronic Travel Authorisation (eTA) through a link via the gov.uk website and I’m sure there’s also a link to the same official application page via the JY website on the relevant holiday page. The eTA costs $7CAD.
The process is quite simple but be sure to use either of the links I’ve suggested because other online websites will charge you more.
JY used to have a department which dealt with all of this (at a cost) if you so wished, but I’m not sure if it exists anymore. I’m guessing that JY expect you to arrange this yourself being as there’s quite a comprehensive review of entry requirements on the relevant holiday page on their website.
Hope this helps.
Mike