Okay buddy, lemme understand you have 4 gray inerts and a red? Simple then use the red stone then pick it up off the ground. Fifthstone opens the hall of secrets.
So use that stone then go look for zixzax he will be standing by each new portal in the homestead when it opens and he says to go through it.
The hall of secrets is the first hand on the left when you turn left from the plac eyou appear at when you twleport to the homestead.
Ignore the rush guide. As stabbey says it avoids combat.
Where did all your stones come from?
You did not go to luculla yet right?
Areas in homestead that are open should be inner chamber, hall of heroes, observatory, an elemental arch, and the fifth opens hall of secrets.