The simplest way to embed a video into your post or page is via YouTube
Create an account with YouTube where you will host your videos.
Next, upload and open the video you want to embed. Right below it, click on the Share icon, then Embed.
Copy the highlighted code, and open up your post or page editor on your blog.
Dashboard > Pages > Add New OR Dashboard > Posts > Add New.
It is usually on Visual by default, so click Text then paste the code from YouTube.
Switch back to Visual formatting, and you will see this frame which confirms that the video has been embedded successfully.
You can control where the video is placed in the post/page by typing your text below and/or above it.
Continue as always and when you publish the post/page, it will have a video in it.