Make sure you've seen this if you need help creating a dataset first! If you already have a usable dataset, follow along here to train a custom model:

Once you have a dataset, you can start by creating a project.

Create a project

Navigate to Rekognition on the console and click “Amazon Rekognition”:

Click Use Custom Labels

On the left sidebar / menu, click projects

On the projects page click Create project

Provide a project name and click the Create project button

Click Train new model

Choose a training dataset in the dropdown, click Split training dataset, and click Train