This textbox is a placeholder for your blog post content. Once you publish your blog plosts through the Wordpress platform you will automatically be able to see your posts on your live Showit website.

It is so easy! Just go to your Wordpress dashboard and create a new blog post (or migrate the old ones). You can add photos to your blog posts in Wordpress and choose a featured photo. To set up a blog category create a new category in Wordpress and then add the slug to Blog Category Page in your Showit template. This process is explained in the instructions doc you received with this template. For each category you have just duplicate the Blog Category Page as many times as needed.
You don't need to edit this textbox content at all. It will be automatically populated with your posts content that you create in Wordpress. This is just the design placeholder for your Wordpress posts.