What do you mean by 'email filters', and how do you view your GMail emails?
Email filters are available on email client software, eg Outlook Express, Outlook, Thunderbird, etc, and generally they are set up using "Message Rules". For example, I use Thunderbird to view and manage my emails from my ISP, and I have set up a rule that emails from a certain email server, (the @name.com part), are moved directly to a named folder as soon as they are downloaded. That is what filtering does, it moves them, or sometimes Junks or Deletes them, as I have set up.
If you use a web browser to view and manage your emails then I am not sure if the same procedure can be used. The email provider decides what options are available in the web page, and perhaps they provide similar "Message Rules" options.
So, tell us more in case I have misunderstood what you are attempting to do.
Does anyone know how to create a filter in gmail that takes in an entire domain... i wanted all "@mycit.ie" and "@cit.ie" to be marked with the lable college. is it possible to do this?