Hi!

The guide for the GUI Wallet users is not ready yet,

However you can migrate / use your GUI wallet balance via Web Wallet interface ( https://wallet.ethereumsocial.kr )

There is a related guide here, you can refer this https://ethereum.stackexchange.com/questions/30967/transfer-mew-wallet-to-mist

Sorry for the inconvenience, we will prepare the GUI wallet around this weekend