To set up a STX token transfer transaction, use the makeSTXTokenTransfer function.
This function requires a senderKey, recipient address, amount to be sent (denominated in uSTX), a network instance, and an anchorMode.
The senderKey is the private key of the sender's wallet.
There are a few optional fields for a STX transfer transaction, including memo, nonce, and fee.
Use memo to add a message as part of the transaction. If you don't want the builder to fetch the nonce and fee from a Stacks node, you can manually set these fields.