There are three seasons. Indoor is usually between January and March, Outdoor – April to July and Cross Country- September to November. It is important to get involved early in a season to get benefit from the training, which can be carried on to the next.
For Elementary school aged, your local School is a good starting point, since many districts have some form of organized track and field activities. At the high school and university/college level, they have their own organizations, such as OFSSA, NCAA, etc. Most Community Information Centres or Recreation Departments are aware of local Clubs and events. A local Sport or Running store is another good source of meet information.