You can create two different types of color fonts in Birdfont, COLR and OpenType SVG. Some programs can use the COLR format and other programs support OpentType SVG.
Begin by selecting the type of color font you want to create in the overview tab:
Open the glyph you want to create and import your letter from an file, Ctrl+I or Command+I is the keybinding.
You need the plus version of Birdfont to create color fonts.