If you own land in Decentraland, then building a great scene is easily attainable to both coders and non-coders alike.

Beginner: To create a simple scene in Decentraland, you should start with the Builder Tool. This simple drag and drop editor requires no coding knowledge, yet allows you to create beautiful scenes and simple games. It has an ever expanding library of pre-made models, both static and dynamic, which you can get creative with at your own leisure.
Visit the Builder Tool: CLICK HERE

If you want to learn a new skill, or top up your existing skillset, the Decentraland University has created a FREE comprehensive video course which will hold your hand through everything you need to know to become proficient at building in Decentraland, even if you have zero experience in coding or 3D modelling.
View the video course: CLICK HERE

Advanced: If you have knowledge of coding in Typescript, or a similar coding language, learn how to use the Decentraland SDK. The Software Development Kit allows you to import 3D models into Decentraland, as well as code advanced games, applications, animations and much more. The possibilities really are endless.
View the SDK docs: CLICK HERE

Points to note:
Build Height Limitations: 1 land = 20 meters. Estates vary. See here.
Build Underground?  No.

–  For more Decentraland building resources, visit the tools and resources section.
–  For inspiration of other creations built using both these tools, view the gallery section.