How do I calculate / draw Bollinger lines?

You can use the "BollingerUpper" and "BollingerLower" functions.

The syntax is:

BollingerLower(series, number of Std Devs, window)

BollingerUpper(series, number of Std Devs, window)

Examples for sek:

BollingerLower(sek, 2, YearLength())

BollingerUpper(sek, 2, YearLength())