It's all up to you, there are people who post their maps and then show progress, but there are also people who never even say that they are creating one before the release. So the decision is yours.
The ambient lighting is also your decision, try to match the lighting with your map though. Like if it's a snowy and chilly map, try to make it have a slight blue tone, if it's a dry and desert map, make it so the map has a orange tone etc... When you get further you can experience with lighting and see what fits best. Also, remember NOT to make your maps dull with black lighting or almost no lighting changes at all, it really helps you get better comments if you give the maps you make attitude

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About the P.S. part...Blackie Chan said everything you need except for 1 thing, there is usually only 1 file you need, and it's the map file, .mpr, there might be screenshots with the maps that usually annoying "professional mappers" put there, now i wonder why