understanding how to use input boxes

The code below opens up an inputbox, right? How does it know to proceed to ask "Example if it is January 1, enter 1."? And why is there a comma after that statement? And finally, where is there another comma and then a "1"? Thanks.

Dim FirstJanuaryDay$, DaysBetween$
FirstJanuaryDay = InputBox("What day in January " & Year(Date) & vbCrLf & _
"is the first payday?" & vbCrLf & _
"Example if it is January 1, enter 1.", "First payday in January:", 1)
If FirstJanuaryDay = "" Then Exit Sub