Pls Help 404 message when trying to open subscription form

[ftruffault]

Than you to all members who try to help newbies as far as they can !

I have a 404 message when trying to open the customer subscription form.
An error page open saying that the connection is not private with this message :
NET::ERR_CERT_COMMON_NAME_INVALID.
So i try to open it, despite the message. Another page then opens with Hostagator logo . I thought Hostgator had the solution, being the hosting...but they say no.
Please help me, i can not go any further because of this deadlock. Any help will be much appreciated.

[ftruffault]

Done : i've got the SSL acces from my hosting. Now i'm trying to see how to insert into my store's URL default page.

[llegrand]

it is on your System > Settings > Details

check the tool tips (the little bubbles) for more info

Turn the USE SSL  to on
Add your HTTPS to the Store secure SSL 

this is give you https links to all the account pages, ordering etc.
If you wish to have your entire site with https - then change the store url to https:  also