Set the branch length using the slider. Each time you click the "Draw Character History" button, a history of character change will be recorded below. Each history has a total length equal to the branch length you've chosen. Colors correspond to different nucleotide states (A, C, G, and T). The length of each colored segment shows the proportion of the branch length the character spends in a given state. Mousing over a character history will give a detailed record of the changes and corresponding waiting times.