How to Complete the task: Check the HTML tag is H1 (Weebly)

The easiest way is to add the free H+ app from the Weebly App Center to your Apps, and then drag it into your post or page wherever you want your h1 or other headers to go. They have different font, colour and size options. 

The second way involves dragging the “Embed Code” element into your page, and insert the following code:

<h1 style="text-align:left;font-size:28px;"> This is your Page's H1</h1>you can see that this specifies the alignment of the text, the size, and the colour. These are all things you can change. Where it says “This is Your Page’s H1”, you’d of course insert your own title.

For Blog posts, the procedure is a little different, you can check out a great tutorial here.