Thanks weenfan, I've bought some stellar from stellarterm. It was confusing at first, but it could be said like this :

- Login or Create an account on Stellarterm.com ( we can use our old secret key from stellar.org too )
- Deposit 5 XLM to the account on Stellarterm.com if we don't have any ballance yet
- on Stellarterm, go to the Manually accept asset,
enter Indocoin on the Asset Code,
enter GDJZKTSK7S5C5ATFX5JCPXW4IBF55XHWMWLDHA5XK6WJEW6NL2RPFTSS on the Issuer Account ID
Click Accept Asset

- Deposit Indocoin to the Indocoin.cash
- Use the generated XLM address from Stellarterm, or from the "Your Wallet Account ID begins with G", and put it in the indocoin address in the Indocoin.cash
- Click "Withdraw" check box on the Indocoin.cash
- Click "execute" on the Indocoin.cash
- Our Indocoin balance will be transferred to the Stellarterm.com

- Start trading on Stellarterm.com