How do i clean my 03 Mitsubishi Montero limited engine?

Hello i have 2003 mitsubishi montero limited which has a very dirty engine this engine has never been clean before so picture how dirty it is, pls help me how do i clean and which part not to be wet or something pls,thanks in advanced.They said the distributor needs to be covered but i dont know where that is, and how much you think will it cost if i bring it to detail shop.|||You can buy engine cleaner that won't harm any engine parts. Or, you can have it STEAM cleaned. It's not expensive. If you are nervous about it, just let a detail shop do it for you.