Okay here are some more hints for beginners

if you want to use an elevator
GO UP TO IT AND AGAINST IT
and press the ACTION button

Elvators and Doors
can sometimes be
Faces
Walls that look different
from their surrounding walls
and
auto Elevators 
that open
and you aproach them

AND

if you cant get a way up
to a platform
look for a ledge
then press the action button
on that ledge
the ledge will come down to you
since its a type of Elevator

also if you cant do that
then you got to find a switch somewhere

in level 20 you'll be put in this kind of situation
so look for different switches

it aint that hard

sound easy enough?

use your map ALOT 
if you are confused
its the "tab" button
on your keyboard