Since Wanchain runs on the EVM as well its smart to familiarize yourself with the EVM first. There are some pretty good reads on EVM already you could start with:
Once you are familiar with the EVM, you should read the Using WanMask page to get an idea of how you can create a dApp that interacts with WanMask. If you want to run blockchain interactions from your backend, you should read the information on smartcontracts, privacy transactions and crosschain as well.
Tutorials