To add a run request, create a page using the example in the link below. Everyone is allowed one outstanding request at a time. You can put up a new request the moment yours is fulfilled, or cancel an unfulfilled one to put up a new one. If a GM fulfills a request, they get a GMP bonus (work in progress, will probably scale with the length of time since the request was posted). After posting the request, you may link the page in the Discord chat to alert the group.
For reference, see Category:Run Requests.