

If you choose " Full-Width Photo", select "Add Image" to choose the photo.
If you choose " Photo Gallery", select "Add to gallery" to select photos. You will be able to select multiple images at one time and can drag to rearrange their order after loaded to the "Image" content area below. You can also delete some or all photos by hovering over one photo and pressing the "X" in the top right corner.

Side note: At any point, if you want to delete a section, just hover over the top right corner and select the red "Remove layout" button.
After adding your section, you can add multiple sections by selecting the blue "Add Section" button.
When you're finished with adding sections, on the right side of the page, there is a toolbar for "Categories", "Tags" and the "Featured Image" (the image that will be at the top of your blog post).
After, you will want to scroll to the bottom of your page, and make sure to edit your post's " SEO Settings". The "Meta Title" is automatically generated based on your blog's title but you can change it if desired. The "Meta Title" bar to the left will change colors based on it's SEO status (try to get a green bar). Under the "Meta Title", is the "Meta Description". Put two or three sentences describing your blog post. Again, the bar under the "Meta Description" will change colors and try to aim for green.
When you have completed everything, press the blue "Publish" button on the top right of the page. It's always a good practice to view your new post to make sure everything looks correctly.