How do you put Land Rover in 4 wheel drive?

Most Land Rovers are FULL-TIME 4x4. Earlier Series Land Rovers (before they were named Defenders) were not. You either had to depress a yellow knob to engage high range 4x4 or pull a red lever to engage low range (this automatically engaged 4x4, assuming your front hubs are locked).

On post Series Land Rovers you have the option of locking the center differential. Series cars did not have a center differential as they weren't full-time 4x4s. Some Discovery 2 models, earlier versions, did not have this as they relied on traction control.

There are some rumors that a 4x2 Land Rover might get produced, this also happened with the Series landrovers. These will/were not able to go 4x4 as they lack the required mechanical parts.