Select Icons from the left toolbar.
Type in a search term for people-related icons, or clicks on the "People" category.
Look out for the customization thumbnail in the bottom corner of the icons: three overlapping circles in different skin tones.
Click on the icon to add it to the design canvas.
Click the Color Tool droplet icon in the top toolbar, and select a different skin tone.
Click anywhere outside the color picker to apply the new color.