How to use Iframes?

But what is an Iframe?
An Iframe is a window from another platform like Youtube. You have to embed an Iframe (in this case in your post). You can embed whatever you like, like a video, soundcloud, etc.
How to use Iframes in your posts? I will show that to you.
First you have to go to Youtube and search the video you want to put in your post. Then you have to go to share below the video.

After you clicked share, you will have the option to embed. When you clicked embed you have to copy the link.

Then, when you already copied the link, you have to paste it in the section HTML of your post.

When you finally did this, you achieved putting an Iframe in your post.