If you're just getting started learning to develop on blockchains we suggest you learn the basics first starting with understanding how Ethereum works and then learning about Smart Contracts which are currently mostly written in the language Solidity. Remember Elastos uses the Ethereum's EVM also and you would run ETH's smart contracts similarly.
After Learning Ethereum / Solidity
The first thing you'll realize after learning about Ethereum, especially if you come from a web development background, is that the blockchain provides the logic and payments layer but is extremely expensive and cumbersome for storing data.
Start Centralized then Slowly Decentralize
We suggest that in the beginning you should store larger files in a traditional storage like Amazon's S3 service and trivial dynamic data in a database. Important things can be put on the blockchain but do not rush to decentralize.
As you understand what DApps are more intuitively then you can rationally reason about which features of your DApp should be prioritized for decentralization.