The highlight of the Amsterdam Gay Pride is the Canal Parade. The parade will start around 12:30 and will take all afternoon. See here a map of the route and the participating boats.
Amsterdam will be full of gay parties this weekend. Here you can find an overview of where and when you drink and dance and a day to day schedule of all party highlights.
The main gay events and parties all take place in the city center of Amsterdam. Visiting for the weekend? August is high tourist season, so make your hotel reservations early. If you visit for a day, please get yourself informed about traffic, public transport and busy areas.