To infuse color into closed areas of a vector network in Figma, follow these steps:

• Select your vector network.
• Enter edit mode by pressing Return (Mac) or Enter (Windows).
• Activate the Paint Bucket tool by clicking its icon in the bottom toolbar or pressing Shift B.
• Hover over a closed region within the vector network. The cursor will change to a droplet icon with a plus sign inside. Click to apply the fill. Once the area is filled, the icon will change to a minus, indicating you can click again to remove the fill.

You can apply different fills to multiple closed regions within the same network.