Welcome to the Ethereum Tutorial!
To get all the branches from git:
git branch -r | grep -v '\->' | while read remote; do git branch --track "${remote#origin/}" "$remote"; done
git fetch --all
git pull --all
Useful links
Solidity documentation: https://solidity.readthedocs.io/en/develop/
Truffle documentation: http://truffleframework.com/docs/