How to make YouTube link

[MomCat]

I cannot figure out how to post a YouTube link so that it will show up as either a hotlink or a picture box that can simply be clickef on. I looked thru the files which showed lots of YouTube links going to those videos, but not *how* to post a link so it shows with the l image box or a clickable link.

I've looked and searched all over, but can't find the instructions

Help, please!