This page describes how to get GRR clients and server components up and running for the first time. If you have Docker installed, and just want to experiment with a container that already has GRR set up, you can follow the instructions given here. It takes ~2 minutes to download the image and initialize the server. Or to quickly start all components and have a full demo setup running follow the instructions here
On successful start of the Docker Compose stack, you should have an admin interface running on port 8000 by default. One Docker container runs the GRR client which can already be used.