Talk to him a few times, ask him to sing for you. If you choose the correct menu options he will tell you he can help you to become a bard.
If you want to be a Bard, you have to bring him a flower. You cannot bring him any buyable flower except Witherless Rose which is sold 1) From a Trader near the east exit of Morroc 2) From the Gift Merchant in a shop east of Lutie 3) From Flower Girl at the lower left corner of Lighthalzen
See the other possible flowers of choice listed above also.
Once you done that, he will tell you to bring a present from a talking snowman named Jack Frost in Lutie and also to become friend with the people there. All these means that you have to complete the Lutie Snowman Quest and come back. See 500px quest section below for Lutie Snowman Quest Guide.
Requirements: You must be an Archer at job level 40 or higher in order to start the quest.
After you come back from Lutie, he will give you a singing test. All you have to do is pay attention to what he sing and 'sing' exactly as him when it is your turn. Remember to read carefully on the capitalization and punctuation.
After you pass, you have two options. You can choose to change into a Bard right away. Or you can decide to get a present from him.
If you choose to get a present, you have to bring him some trunks. Read the next part for the possible presents made from each type of trunks.