The effects of berries are random each round, and only the Chemist has the skill needed to identify them.
When two berries are combined, they turn into dyes based on the colors combined. The dye will go into your items tab and is used by double-clicking. Once double-clicked, a mini pop-up menu will appear. You then select what clothing to dye. The clothing changes color to whatever color the dye was.
See also: Paint
Berries and dye can be used to paint on various surfaces and structures. With the intended berries or dye, right click on a surface/structure, click paint and choose what color you want to color with (if you have only one type of berry or dye, it'll automatically paint with that color without a popup). With this you can make masterpieces, graffiti, and color with multiple colors on one thing (only one can be used at a time).