This is probably a bit redundant for you, but I couldn't tell exactly where you were having trouble.
For the new masteries, you need a Mastery Book. Which you can get in one of two ways.
- Complete any of the 3 bard masteries quests and you will get a Mastery Book.
- Complete Hawkwind's quest and you will get a Mastery Book.
Then, you need to get the Mastery Primers, these are different from the Mastery Book.
Think of the Mastery Book like a spell book, and the Mastery Primers like individual scrolls that activate the spells in the spell book.
When you have a Mastery Primer, double click on it to consume it.
Next, right click on the Mastery Book, choose the "Switch Mastery" option, and select the mastery you want to use. (This must be a mastery for which you have consumed a primer.)
Finally, double click on the Mastery Book to open it. The icons for the "active" mastery, the one you chose in the previous step, will be on the right side of the book.
Also, all of the existing Bard Mastery Books (with 6 spells) were converted to Mastery Books (with 45 spells). Some of the books did not convert properly and ended up as Mastery Books (6 Spells). These are bugged.
If you are using a Bard Mastery Book (one you had from before Time of Legends) that was converted to a Mastery Book, that particular Mastery Book may not be working correctly. Highlight the book to see if it has 6 spells or 45 spells. If it's only 6 spells, go do one of the quests mentioned above and get a new Mastery Book (45 spells). Any primers your character has consumed will be remembered and available with the new properly working Mastery Book (45 Spells).