Embedding a Spotify Playlist:
To embed a Spotify playlist, you need to get the embed code. First, click the three dots on your playlist, then under share, select "Copy embed code."
This will give you the iframe code. While drafting your post, click the plus symbol on the left side of the writing area. Select "HTML: Insert a raw HTML code," then, paste the iframe code into the textbox. If you want to make it a different size, you can change the width and height. You can also center it by surrounding your code with first "<div style="text-align:center" then ending it with "</div>".
Embedding a Pinterest Board is a lot more finicky. First, you'll need to use the Pinterest widget builder, then select what you would like to embed. For this, we'll be embedding a board. Take the full URL of whatever Pinterest board you want to use (should look like https://www.pinterest.com/[username]/[board-name]/). Then pick whatever size you want, or make a custom one for yourself.
Copy and paste the code given by the widget into an HTML textbox:
You can also center it by surrounding your code with first "<div style="text-align:center" then ending it with "</div>". Then, you need to include the second half of the code given:
This part just needs to be anywhere on the page, but it's easiest to keep it within the same box of HTML just in case.