Wp Theme Multiple Content Help?

Hello,

I recently paid for a template, which can be seen in a live demo here

– https://www.wpnow.com/demo/#gamenow

The top content area to add images i have been told to do the following

To setup the featured posts section you need to add the following to the Custom Fields on your post page:
Names: thumbnail and featured_thumbnail
Values: url to those images
*You can use the WP Post Thumbnail Plugin to create the specific image sizes and insert their URL in to the Custom Fields automatically. Click here to view a tutorial on using the WP Post Thumbnail plugin. You can also insert the information manually by uploading each image size. For image sizes, please see the Common Image Dimensions FAQ for your particular theme.
To Determine which Posts are Displayed in the Featured Section:
1) Create a new category titled Featured or something similar.
2) In admin, navigate to the Theme Options Panel located under Appearance. Locate the drop-down menu under Featured Category. Select “Featured”.
3) Any posts you want shown in the Featured section, just assign it to the Featured category.

I have NO clue could anyone help me

my site – https://www.xronn.co.uk

Many thanks!