You would need to find out what variable in the library stores the information about what time of day it is. The code "If IsEvening" isn't valid. I haven't used that library, but if the time of day is set as a boolean attribute on the game object called IsEvening, then it would be something like this:
if (game.IsEvening = true) {
msg ("It is evening.")
}
else {
msg ("It is daytime.")
}