This tutorial will cover the usage of OpenTuner, a open source framework for building domain-specific multi-objective program autotuners. OpenTuner supports fully customizable configuration representations, an extensible technique representation to allow for domain-specific techniques, and an easy to use interface for communicating with the tuned program. A key capability inside OpenTuner is the use of ensembles of disparate search techniques simultaneously. Techniques which perform well will receive larger testing budgets and techniques which perform poorly will be disabled. OpenTuner has been used by a number of different projects to build domain specific autotuners.