Never minted and have one question do I have to do it using new mew address or this address where I hold my tokens?
If you use MyEtherWallet,you dont need to using new mew address.
You can execute mint() function,but you need to hold more than or equal to The Minimum Coin Age.
Step-by-Step PoSToken Mining:https://bitcointalk.org/index.php?topic=2110712.msg21934703#msg21934703
PoSToken Mining Calculator:https://calculator.postoken.org