Do you have photobucket.com? If not, join that.

Once you upload your pictures You will see 4 small "windows" under the picture when you put you cursor over the picture. The 3rd window shows HTML code. Left click on that one and it will show copied (for just a second).
go to where ever you want to post the picture and right click and click paste.
It will look like a bunch of gobbldie gook. When you go to preview message the pictucre will show up.

There are several explanations but below seems the clearest to me.

Here is a link that might be useful: here's a very easy explanation.