If you don't see such a link on the left hand side, once you've signed up for an account and logged in, use this handy link to browse directly to the 'create event' page.
Enter a title under "Title:" e.g. "Steve Jobs to talk about iTunes and ecommerce", select a neighbourhood under "neighbourhood", one or more topics under "topics" e.g. "Fashion", a start time under "Start:", optionally enter a location under "Location:", and some text under "Details:"
If you are happy with what you wrote, click on "Submit" and you are done.
Otherwise, click "Preview" to see preview your event.
If you are satisfied with your event, click on "Submit" and you are done.
If you are not satisified with your event, make the appropriate edits and then go back to the preview step.