If you don't have any custom emoticons yet on your MSN Messenger you are falling behind the times. Everybody is using MSN Emoticons these days so why not jump on the band wagon. It is actually really simple and only takes about 30 seconds.
The first step is to find an emoticon you like. You can download tons of emoticons from web sites around the web. A few web sites that have tons are
http://www.msnemotions.org
http://www.sherv.net
http://www.mess.be
Once you've found some emoticons or smileys you would like to add to MSN, save them to your computer. I'd suggest making an emoticon folder in your 'my documents' folder so you know where all your smileys are and to prevent any of them from getting deleted accidently.
Next, open MSN Messenger, and in the Tools Menu, click 'Emoticons...'
You will be brought to the emoticons menu! Once in the emoticons menu, click the 'create...' button located on the right.
You will be brought to the 'add a Custom Emoticon' window.
Follow the instructions and pick an image, give it a shortcut(I prefer to wrap the shortcut with brackets), then name your emoticon. Click ok and you are done!
Go message a friend using the shortcut you create and they will be sent the emoticon that you created!