First, assemble your basic document layout. Doing so will allow you to embed videos properly.
Below your body tag, insert a video tag and then start another line.
Once you have your video, find an option on the page to share the video or embed it, on many platforms this is an option, the example below is on Youtube. Copy the code provided.
Use the "< video> tag, start a new line, then paste the link you obtained from your video (from step 3).
Start a new line and close the video tag.
Your embedded video should look something like this: