Hi Suzanne, I really can't say it any different than the corresponding lesson to which you refer.
Tout-toute / tous-toutes are the different forms, masculine-feminine in singular and plural.
And depending on how you use it, it can mean different things:
J'ai oublié tout. -- I forgot everything.
J'y ai pensé toute la journée. -- I tought about it all the day.
Nous sommes tous arrivés ensemble. -- We all arrived together. (a male or mixed group)
Nous sommes toutes arrivées ensemble -- We all arrived together. (an all female group)
I hope that helps, -- Chris (not a native speaker).