If you are in a situation where you are the only person available, and you need to move the person immediately, you use the drag carry.
Stand behind the person's head, and use their clothing to drag them backward, supporting their head and neck for as little movement as possible.
Remember, this is only in an emergency situation where they must be moved immediately. Doing this can result in severe spinal injury aggravation resulting in paralysis or impaired motor function, so if at all possible you should wait for a second rescuer with equipment, or an ambulance.
The two-man fore-and-aft carry is used to transport a conscious or unconscious casualty and is the preferred two-man carry for moving a casualty for a long distance.
A "fireman's carry" is the recommended method if you can lift and carry the victim. Otherwise an improvised litter if this is practical. Any method is limited by the capabilities of the transporting person.
Fore and aft carry
Fore and Aft carry
Fireman's
fireman's carry
firemans
Firemans' Carry
Firemans Carry
Fireman's
for and aft
The preferred method is on a litter or a stretcher. You can improvise litters--there's a way to wrap a poncho around two long poles so the victim doesn't fall out.