As for updating your map, this is how it goes:
1. Change your map the way you like and save it.
2. *WARNING* If you have subscribed your map before you edited your map, two maps with the same name will appear in your list of saved maps. Save and overwrite the lower one in the list, saving it on the upper one will cause two different problems:
- If you restart your game after you saved, the new edited map will be automatically be replaced with the old map you once uploaded to steam workshop. You basically lost all work you did since then.
- If you saved it on the upper saved map and you immediately try to upload it to steam workshop it will actually completely destroy your map, you will NOT be able to get it back unless you made a backup of it with a different name.
3. If you did not subscribe to your map, you can do it now in steam workshop.
4. Start CSL and go to your content manager, your map will appear twice. One, the upper one, will have a "view on steam workshop" button and an "update" button.
5. Click the update button. A preview image will now appear with a big "update" button, do NOT press that button.
6. Instead click on a very small map icon in the lower right corner of you preview image.
7. It will open a temporary map which contains the stuff that will be uploaded: a map called "content" and a file called "previewimage".
8. Open both the map "content" within your temporary map and seperately open the following directory: "C:\Users\*** your user name ***\AppData\Local\Colossal Order\Cities_Skylines\Maps". There you will find your edited map. If you're not sure, sort by date and the newest will be on top.
9. Copy the *yourmapname*.crp to the content folder and replace the .crp file that's within.
10. Go back to CSL and now DO press the "update" button and voila you have your map updated.
Please say if I have to explain myself, english is not my native language.
I allway's recommend to make a back up of your saved map with a different name before you upload it. It's a tricky process and I allready lost a map because of it.