Raising money by a sponsored run
Organise a sponsored run for the serious runners in your community. Of course a shorter course for the children, and those adults who do not fancy the idea of the longer course! You need to find a safe enjoyable place for the event. Local park areas and school grounds (normally emty at weekends) can be reasonable places for this type of event.
You may need permission from local councils or the police if the course includes pavements or roads.
You amy also need to get a permit from the local council in order to collect money during the event.
You may also need to provide water etc. for the runners and arrange for medical backup to be available. Check with the local council!
It may be useful for you to contact a local running club. The chances are that they have organnised events in their area before. They will probably know who you need to contact and what you need to do in order to be allowed to hold an event on public roads and surfaces.