The myetherwallet site doesn’t list DAG under the default tokens yet, so that you have to create it for yourself.
There could also be a “wallet” tag for question on this forum, among others.
For the time being, for those who want to do it, the contract hash is
But as an aside, always be sure to be choosy on browser extensions when it comes to using wallets integrated in web-system.
Screenshot from myetherwallet.com: