Confused about enable https on vps

I've a vps, where ive installed ubuntu and apache2 server, and ive several laravel application.

Configured via "domains.conf"

The address are in format like:
>
> vpsName./site1
> vpsName./site2
> vpsName/site3
Im confused because ive found this:https://www.ovh.co.uk/ssl-gateway/

but when i'm trying to set up the free service ( the first on the left of the 3 services available on the page) its ask me about the domain name, but if I write:

> vpsName.some

its give me an error message. About providing a valid domain name

So how can i set up on https for my server? is this the right way or ive to install stright in to the machine via apt ?