WS2811BladePtr is an older version of WS281XBladePtr. I recommend using WS281XBladePtr instead this documentation can be helpful to understand older config files though.
WS2811BladePtr takes 7 arguments, but only two are actually required.
WS2811BladePtr<leds, config, data_pin, power_pins, pin_class, reset_us, t1h, t0h>
All the arguments except for "config" behave the same as in WS281XBladePtr.
The config specifies both the byte order and the frequency. The byte order is one of:
WS2811_RGB WS2811_RBG WS2811_GRB WS2811_GBR
If no byte order, it defaults to RGB, which is probably not what you want. The frequency is one of:
WS2811_800kHz WS2811_400kHz WS2813_800kHz WS2811_580kHz WS2811_ACTUALLY_800kHz
Note that the 800kHz ones actually use 740kHz. And the WS2811 and WS2813 ones are identical since all of them use a timeout of 300us.
The frequency and byte order are combined by using the | operator, like this:
WS2811_800kHz | WS2811_GRB