There's no guide other than the help pages.
Never used this but I'm guessing you need all your kids on the same SSID, separate from yours, so that they share (& compete for) the limited bandwidth you set for them. However there is no way I see for sharing this equally; they just compete for it.
Tho' I seem to remember there was a post round here that said this limited bandwidth thing didn't work, but that was with old Orange firmware.
1999: Freeserve 48K Dial-Up => 2005: Wanadoo 1 Meg BB => 2007: Orange 2 Meg BB => 2008: Orange 8 Meg LLU => 2010: Orange 16 Meg LLU => 2011: Orange 19 Meg WBC