Passenger Planes General
There are two main forms of jet engines, one with a propeller (called turboprop) shown at the bototm of this page, and one without like the Lufthansa B747-400 shown here.
Aircraft wheels
On the ground a plane needs wheels on which to "taxi", that is, move around. Generally the nosewheel is used for steering on the ground. After an aeroplane has become airborne it will retract these wheels to reduce drag and fly faster.
Not every plane can retract its wheels, but the reason that those that do is to reduce drag.
Planes general
Aeroplanescome in various shapes and sizes as shown by a few examples on this page. It doesn't matter if they have one wing, or if they have two wings as in older planes. They all use the same principle to fly. They all need an airflow over their wings to generate lift
The menu item "How a Plane flies" explains how a wing enables a plane to fly. It must be remembered that a plane has to move forward to create an airflow over the wing. Engines propel a plane forward.