SEM is DPOS(if i understand correctly). you can "mine" this if you become a validator. You can find more info here --> https://github.com/semuxproject/semux-core/blob/master/docs/Delegates-and-Validators.md

other ways to get SEM are the following:
*Buy them on #trading of the official discord. Beware of scammers! OR directly from Stocks.Exchange
*Join the BTC Airdrop (Completed), ETH Airdrop (Completed), other Airdrops (that might follow)
*Join the Signature Campaign (Already Running)
*Contribute to the communityVote for a validator who is willing to share block rewards --> meaning you become a delegate (vote for a validator that shares block rewards with his voters). More info again at https://github.com/semuxproject/semux-core/blob/master/docs/Delegates-and-Validators.md