getting a video into my blog

I’m trying to get a youtube video onto my blog but am having difficulties, I’m not excatly a computer whiz but I thought it would be a case of copying the embed code from youtube to the html part of my blog and clicking update, when I did this the video didnt show, I looked at the html and it had changed from what I pasted, I posted anyway and took a look, I found that the video hadnt been posted and the text of my other posts had been spread across the page when its normally fixed width, I deleted the post to amend that problem but am unaware of how I can put the video up

any advice?