Will creating an obligation come under state?

I want to create an obligation stating all the details about a particular property which is to be transferred to another party. So is creating this obligation a state?

Yes. In Corda any shared fact on the ledger is a state.

In general, CorDapps decompose into three main parts:

• States, which describe shared facts
• Contracts, which govern the evolution of these shared facts
• Flows, which allow your node to execute some process, generally related to updating the ledger's shared facts