"The plugin generated…" Error

Here is a link to my plugin code (.php)

For some reason, I receive this error whenever I activate it..
“The plugin generated 222 characters of unexpected output during activation. If you notice “headers already sent” messages, problems with syndication feeds or other issues, try deactivating or removing this plugin.”
This is my first time developing a plugin, as it’s a little messy. I am not sure why this is occurring, and would be grateful for any help.

Last question. When I tried to activate this on my other site, the footer seemed to be messed up while this was active. Could this be because of this?

Any support would be greatly appreciated!
Thanks,
George