Don't overlook the Help that comes with your editor. Various map editors are available. But the same principles apply to other editors. By applying Textures to brushes, you can make your map look like anything you want. Use Entities to create cool scenery and special effects .
More complex effects require entity scripting .
These things require time and attention. Persist in your efforts, and you'll create excellent maps. Single Player - The best SP games respond to player actions with an unfolding story line Typically built from multiple maps with level changes between maps. See also Maps page. After every compile, review your process window .