If you do not have $ELF, use Portkey wallet to buy $ELF with fiat and transfer $ELF from aelf MainChain (ELF) to aelf dAppChain (tDVV). Lastly, swap $ELF for $SGR using AwakenSwap dApp.
If you do not have $ELF, you can buy $ELF on CEX-es and transfer to your Portkey Wallet. Ensure $ELF is on aelf dAppChain (tDVV). Lastly, swap $ELF for $SGR using AwakenSwap dApp.
If you wish to buy $SGR from a centralised exchange, you can first purchase $SGR from Gate.io. Then, using the ETransfer dApp, bridge $SGR from Ethereum (ERC20) to aelf's dAppChain (tDVV).
If you wish to buy $SGR from a decentralised exchange, first swap for $SGR on Uniswap. Then, using the dApp eBridge, bridge $SGR from Ethereum (ERC20) to aelf's dAppChain (tDVV).