Hi [matrix]Neo[X], as Zero says NUS has this built in. There are also 4 individual messages (Next NUS will have 9) that you can use. On the site are pages to how to make scripts too.
This page has the auto message one.
If you are new to scripts I suggest you read the whole walkthrough. Most people find using NUS easier as it does it all for you, but if you want to make one yourself those pages will help you. If you need any more help with it, by all means post back here, so that we can look it over for you.
This topic show you how to make individual messages,
http://009.web-fun.net/forum/viewtopic.php?t=302