How to unstake stETH from lido?

Could you please explain, in a step-by-step manner, how to effectively unstake stETH from Lido? I'm particularly interested in understanding the process, including any prerequisites or necessary actions that I may need to take. Also, are there any fees associated with this process? Additionally, could you clarify the estimated time it might take for the unstaking to be completed? It would be helpful if you could provide any insights or tips that could make the process smoother and more efficient. Thank you for your assistance in this matter.