Solidity
The course about solidity on web3js https://coursetro.com/courses/20/Developing-Ethereum-Smart-Contracts-for-Beginners
The course about solidity instance http://solidity.readthedocs.io/en/v0.4.24/solidity-by-example.html
The youtube course about solidity https://www.youtube.com/watch?v=UujjTmkjWI8&list=PLVR6_kyVYQd7z0CeV9xcy-gf6jKrO6cTP&index=2