Create a game
First a game has to be created in Bedwars. Think of a name and execute /bw add [name]. In the following step you can set up the game with /bw setup [name], set the lobby spawn and a hologram with statistics.
Create a map
In Bedwars, players can choose between multiple maps in a pre-game vote. With /bw setup maps you open the menu for setting up a map. Now click on Add map and follow the setup process that will guide you. When you're done, you can also add spawners by clicking on the corresponding menu item. You can also create NPCs as a shop with a click on the player's head. Of course it still works that villagers automatically can be used as shop.
If you have created and set up one or more maps, you can specify the map at /bw setup [name]. To do this, click on the map item and select either Automatic or a map.