The transaction hash is a unique identifier for each transaction on the Celo blockchain. You can find yours from the transaction in your Valora home screen. Tap the transaction and you will be taken to a page containing your transaction details. At the bottom of the details, tap the link labeled "View on CeloScan."
A browser page will open up and you will see the transaction on CeloScan. At the top of the Overview section, you will see your transaction hash. You can copy it by tapping the icon next to the transaction hash.
If you'd like to explore CeloScan further, check out our article on how to navigate a blockchain explorer.