How can I create a transaction or smart contract that uses a custom Solana token?

SolanaSolana
$32.11
‑6.82%
self.solana1m ago
Hey, I am trying to create a smart contract using my own Solana token instead of using sol or lamports. Is there any way of specifying what token to use in a person's wallet in a smart contract? Thanks. Update: Please note that the token is an SPL-Token