To add a headshot and other images to your IMDb page, you'll need an IMDbPro membership. If you already are an IMDbPro member, you will need to first claim your page. Once you've claimed your page, you can add images to your page.
If you haven't joined IMDbPro yet, you can try IMDbPro for a 30-day free trial. If you don't already have an IMDb page, you'll be given the option to create one, when you claim your page.
You will need an individual membership for each IMDb page that you wish to claim. If you already used your membership to claim your page, you will need to create a separate membership to claim a second page.
To add an image to an IMDb title page (i.e. movie, TV show, TV episode, video game, etc.) simply select the "Add Image" option located at the end of the image gallery. For more information, please see IMDb Title Images: Frequently Asked Questions