In all cases, use the function name followed by a list of expressions, separated by commas, of data type corresponding to the function prototype.
The result of a function call can either be assigned to a variable
nToday = Today()
nDateEaster = GetEasterFor(nYear)
or it can be used as parameter of another function call, as below, in nested function calls.
nWeekDay = WeekdayOf(Today())
nMayFirst = FirstDateOfMonth(YearOf(Today()),5)
Some functions are called void, because they do not return any result. These are usually function that act on the databases. They are called simply, without assigning their result.
To find out which functions are available to you, and how to use them, you can either look up the Built-in Functions section below, or from within the Code Editor press F3 to invoke the Q++ Code Completion feature.