Hello Charles-Henri! To get started you'll need to log in to the hosting provider that serves DNS for your domain mymailhosting.com and create a couple of A records. If you're not sure who provides your DNS you may need to reach out to whoever normally does your IT and have them add A records for the minimum hostnames outlined below:

Those A records should point to the IP address of your SmarterMail server. Once created, you can then add an MX record to that same DNS area that points mail deliveries for mymailhosting.com to mail.mymailhosting.com and at that point the basics are covered. You should also deploy SPF records, DKIM, etc but these can be taken care of once your server is deployed initially. 

To get the SSL set up you can then head into IIS (if using Windows) and add HTTP/HTTPS bindings (wildcard bindings work best) for those same hostnames and finally, enable automatic SSL certificate generation in SmarterMail under Settings>SSL Certificates to have SmarterMail initiate a certificate request for those hostnames you added to DNS and IIS. 

That should get you started and I recommend investigating the KB section here on our portal and our help at help.smartertools.com for assistance with any additional steps you want to implement after getting the basics taken care of. Let us know if you have any questions along the way!