On the overview page, you have a button "Add Service":
Then, you are presented with a form to enter the service details. A service can be either:
- A repository containing a Dockerfile: enter the repository address
- A Docker image: enter the image name
You can also choose how much memory you want to allocate for that service. If you don't specify enough memory, the service will not work. It's best to monitor your service so you know how much it will need.