Just posting this to give a quick illustration on building stairs since there is so much random and sometimes confusing information out there.
Each step is 2 Levels.
Foot Stools, Damaged Books, Horse Dung, snow piles, etc....once locked down can be walked on.
By using Raw Fish Steaks, you can cook the steaks out from underneath. Don't waste your time with cooked fish steaks and eating them as others have suggested. You'll just end up full and looking for alt characters.
In order to cook the fish steaks out from underneath, you need to release the Foot Stool AFTER you lock it down initially. You then just 2x click the Fish Steaks and target a Heating Stand. Once all the Fish Steaks are cooked, Lockdown the Foot Stool again. Then move on to the next Foot Stool.
Once you are past 5 Fish Steaks (or levels), you no longer need to release the Foot Stool to cook the Fish Steaks out from underneath. This should be your 4th Step.
When it comes to placing Foot Stools on the edges of houses for Bridging and climbing to the corners of Keeps/Castles, you need to be at the appropriate height to place the stool. Some spots are harder than others to place and some simply will not allow you to place a Foot Stool upon them. Sometimes it is easier to find a simple path to the corners, then once up there go and place the stool where you really want it. Just play with it some and you'll eventually get it.
A handy trick is using Razor's Where command. Simply type "-where" without the quotes in game and it will give you your players X,Y, & Z coordinates with "Z" being how high you are. This will help you check that you've got your steps right.
If anyone needs to be shown how to do this, just get ahold of me when i'm online and i'll be glad to show you how to do it.
P.S. Small Square Tables are 6 levels high if you want to use those in place of 6 Fish Steaks.