If you are looking at this from IntelliJ IDEA you can start by expanding the _project_ tab on the left. You will find a template program in `src/main/kotlin/TemplateProgram.kt`
You will find some [basic instructions](https://guide.openrndr.org/#/02_Getting_Started_with_OPENRNDR/C00_SetupYourFirstProgram) in the [OPENRNDR guide](https://guide.openrndr.org)