Where are you getting confused?
In order to read the game better, I went and immediately installed a graphics mod when I started playing. I'm noticing that while helpful in-game, reading what people use to signify items/locations is amazingly difficult for me.
So did I (the ASCII gives me headaches). The basic premise is that with ramps, you need to butt them against a solid wall piece, with open space above it.
Side view of functional ramp:
(This will work, with W representing a solid, un-dug piece of ground or a constructed wall.)
/W
/WWW
Side view of NON-FUNCTIONAL ramps:
(This will not work, with _ representing a floor (natural or constructed) and / representing a ramp.)
_/_
/___
How you arrange these is up to you, but always keep in mind that a ramp onto a floor-only piece will NOT work. I often use a spiral ramp for my main fortress entrance, and a 3x3 up-down staircase for the interior areas that only my dwarves should enter.
Staircases, similarly, require that you have both an up and a down connecting. An upstairs with no downstairs above it cannot be ascended by dwarves. A downstairs with no upstairs below it cannot be descended (unless you can fly or burrow through the rock below). An up-down staircase works identically to this, but represents both an upstairs AND a downstairs on the same floor tile, allowing both an upstair below it and a downstair above it to both function correctly.
So, for stairs, these are not-functional stairs in side-view:
(downstairs with no upstairs below - dwarves can't descend, flying critters
can enter from below)
V_____
Upstairs with no downstairs above, dwarves can't ascend. Flying critters can enter if there's no floor above the stairs.)
____
^
These are functional, in side view:
Single matching up-down pair on different floors.
V_
^_
Alternating up-down pairs, note that they're matched above-below.
V_
^V
_^
Finally, a three-floor staircase:
V___
X___
^___
Where V is a downstair, ^ is an upstair, X is an up-down stair, and _ represents a floor (natural or constructed).
Hopefully, that's clearer. (...and welcome to Dwarf Fortress, where the answer is always
Magma.)