FCL staking is available on SushiSwap dApp on the Gnosis chain. To stake your tokens, you will need to have FCL on the Gnosis chain, which you can have by either:
Transferring FCL to Gnosis through the FCL-Gnosis bridge
Swap xDAI for FCL on the dApp or on another chain (e.g. USDC for DAI on Ethereum). For the latter, you will need to use the Gnosis Bridge to swap it for xDai on Gnosis. To swap xDAI for FCL on the dApp you will need to have xDAI that is available on exchanges like SushiSwap.