Hi,
If your site is new then simply create posts with featured images and you will get a look like demo by default. If still wish to import demo content, then check Quick links in the member area.
Note: We do not recommend importing demo content as it will create unnecessary posts and users that you have to edit and delete. If you are just testing then you can do so.
Refer docs for theme setup: https://themonic.com/online-documentation-usage-guide-for-iconic-one-pro/