Very few adults will be able to resist making a donation to a kid asking for help. Just look really sad and tell them you have no playground anymore. Here are some ideas:
  Make "TorontoPlaygrounds.com" flyers and signs and put them up at your school, in your neighborhood, and at local stores.  
Print blank copies of the donation form and give them to freinds and neighbours. Don't forget to select the school(s) on the form before you print it.
Ask the managers of local stores to make a donation. Donations over $500 are recognized on the site. Donations over $5000 get a company logo on this site (and a link to their website).
Organize a bake sale at your school or at a local community center or mall to raise money.
Spread the word about this site. E-mail friends and neighbors.