To add a team member, go to your dashboard and navigate to Team > Add New.
The title of the post will be the team member name, the featured image will be the headshot, and the body of the post will be the body of the team member bio. The ideal size for the team member headshot is 1920 x 1280px. This way it will show up nicely in the page header area on single team member pages.
To have your team members display on a page, such as your About page, simply select the Team template from the template options for that page. Team members will then automatically display at the bottom of that page and you can add content above it.
To have your team display in a widget area, go to Appearance > Widgets. Drag the “Showcase Team Grid” to the Front Page 4 widget area. Here are the settings I used for the demo:
For more information on setting up the front page widget areas, please see this page.