I noticed tonight my robots.txt file is using http"s"://www.racingtrader.ca/sitemap.php but I can't open it? but I am able to use http://www.racingtrader.ca/sitemap.php am I using the wrong URL.
"If" you have tried to make your website HTTPS, it looks like it hasnt been done properly. It needs fixing throughout the website. Once you have fixed the security issues, you should be able to download the HTTPS sitemap as well. As a first timer on your website, I can easily open HTTP version of the website which is live but when I try to open https version of you website I get a warning message saying that The owner of www.racingtrader.ca has configured their website improperly. To protect your information from being stolen, Firefox has not connected to this website. Once you have fixed the HTTPS security issue, you might want to consider canonicalizing your HTTP urls to HTTPS urls. Contact a web developer for fixing HTTPs
And if you are using WordPress there is plugin called force https, install this all your website will run on https