Open Emerald first, and follow these first few steps
1. Select any map, here, it's LITTLEROOT TOWN
2. Click on the icon indicated below.
2. Rename your map, change the map size, and select tilesets to use.
3. You can keep the name and size, but you must select 2 tilesets for you to make the map.
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4. Once you've created your map using the tilesets to the right when your new map appears, it's time to add it to the already loaded banks of maps in the rom.
5. Click the icon indicated below
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