Creating transaction with using blockcypher https://api.blockcypher.com/v1/btc/main/txs/new?token={{TOKEN}}
To use BlockCypher's two-endpoint transaction creation tool, first you
need to provide the input address(es), output address, and value to
transfer (in satoshis). Provide this in a partially-filled out TX
request object.

From where can I get input addresses to create transaction?
It's simply the address(es) that you want to send Bitcoins from.