About:

Once you install the SSL cert on your website, you will need to redirect http to https site to make sure that the site will open in secure mode

Steps:

Click on “Plesk Admin”
Create the SSL cert (there is another note here how to create a free one), install it for your website.
Under the domain you want to redirect http to https, click on “Hosting settings”
Under “Hosting Setting”, follow the pic below
1 – make sure the domain is correct.
2 – choose the url without www
3 – select the “SSL” and “Permanent”, choose the cert installed already from before.