The concept of the Uitmarkt is that the public gets to see small samples, usually 15 minutes, of the performances and shows of the coming season. On a large outdoor market, theatre groups get the opportunity to present themselves.
The (about 450) sample shows are mostly free, and can be seen in many venues and several temporary outdoor stages.

This year the Uitmarkt locations are in the centre of Amsterdam (a map of the area is on the Uitmarkt website, see below).

The opening performance is on Dam Square, 8.50 pm Friday evening.
On Saturday and Sunday there are performances all over the central part of town.
On Sunday, 9.20pm, the weekend is closed off with a 'Musical Sing-a-Long', on Dam Square.

More info is on the Uitmarkt website (mostly in Dutch, with English summary).
A map of locations is on http://www.amsterdamsuitburo.nl/uitmarkt/plattegrond .