There are two straightforward guides to creating and editing calendar items available on the ITS webpages, which should provide all the information you need if you're not already familiar with SiteBuilder.
However, the form is very intuitive to use. Simply go to the events calendar page and click on the green '+' symbol that appears at the top of your selected date when you hover over it. Next fill in the Title, then a brief summary of what the event is and who can attend. If the event already has a webpage then you can copy the url (web address/domain) into the URL box, if not, then click on 'create the detail for this item now' toggle button.
Next you'll need to add your start and finish time, together with the location of the event. Finally, you'll need to choose your tags. You should select only the categories that apply for your event in terms of the department organising the event or departments that would be interested in the subject matter. Please contact Internal Communications internalcomms at warwick dot ac dot uk before creating any new tags.
Once you are happy with the entry click 'done'.