If I hold ETH?
People who own ETH coin do not need to take any special measures unless the exchange, web, mobile, or hard wallet they use tells them to do something. As Vitalik Buterin explained, theres no need to dump your non-Constantinople coins.
I could not find any information on how to get the forked coins. I have some ETH in my Mew wallet but I do not see any other coins in there. Any information regarding that?
Blockchain did not divide, so there are no new and old coins. Anyone who has ETH or tokens based on the Ethereum platform can use them as before. Only technical conditions have changed, mainly concerning on ETH mining.