If you put your motorcycle in gear without the engine running, nothing significant will happen. The motorcycle will remain stationary as long as the clutch is engaged, which is the usual state when the engine is off.
When the engine is running, engaging a gear with the clutch lever pulled in allows the power from the engine to transfer to the rear wheel, propelling the motorcycle forward or backward, depending on the gear selected. However, without the engine running, there is no power being generated to move the motorcycle, so putting it in gear will not cause any movement or damage.
It's worth noting that attempting to shift gears without using the clutch while the engine is running can cause the motorcycle to lurch or stall, as the clutch is necessary to disengage the power from the engine temporarily during gear changes. However, when the engine is off, the gears can be shifted without the need for the clutch.