You are encouraged to look at the Contract SDK itself, although that is not required in order to build contracts on the Orbs Network.
Every feature of the SDK is documented at the Orbs Contract chapter of the Contract SDK documentation. The Contract SDK is also published as a Go Module to ease usage when developing a contract. (what are Go Modules - from the golang blog)
Having that said, the examples in the Contract SDK project can be useful in order to assist with getting started on creating more complex contracts.
Cloning the SDK
Download the SDK to your computer by running the following in a terminal
go get -u github.com/orbs-network/orbs-contract-sdk/...
It is recommended to avoid cloning the repo manually with git because the SDK has to be placed in the appropriate path within your Go workspace. The SDK also includes a few git submodules which may be a little tricky to clone recursively.
Quick tour of the SDK contents
The SDK will download to your Go workspace, typically at