okay, the reason why you can't copy and paste photos into the internet is because they can't link to your computer and show them through there. They have to be hosted on a server, which then you can give a link to (like
CODE
http://www.example.com/image
) Then they could click on that and be redirected to the server that has the picture. Instead of doing this though, you can also upload it as an attachment on yahoo mail. some sites will only accept certain file types.
So, in short, you can't copy and paste a photo into the internet, because it has to be somewhere that another computer can get to. They can't directly connect to your computer. Thus, you have to get it on a server that will always be around to give them(or anyone else who gets ahold of the URL) the picture.
To send pictures, you have to get a server that will hold(host) the pictures on for you. photobucket and imageshack.us are two sites that allow you to do that. If you want it private though, you've got to go through emails. anyone can access those files on photobucket or imageshack if they get the link.
Also, remember yahoo mail, and most other emails are also limited to 10MB of data per message. So, you can't send videos or anything like that.