This lesson is an introduction to GPU programming using the directive-based OpenACC paradigm. The course consists of lectures, type-along and hands-on exercises. Topics covered include the architecture of the GPU accelerators, basic usage of OpenACC, and how to control data movement between CPUs and GPUs. Basic optimization of the code will also be covered. After the course the participants should have the basic skills needed for utilising OpenACC with new or existing programs. The participants are assumed to have knowledge of Fortran and/or C programming languages. Since participants will be using HPC clusters to run the examples, fluent operation in a Linux/Unix environment is assumed.