Dragon souls not activating new words

So if I understand correctly you can learn new words and the souls will activate these words. I just killed a dragon and when it died it looked like I absorbed the soul but it didn't unlock any of the words I have.

I noticed some dragons actually have a name so do certain dragons unlock certain words?

Dragon souls can be saved, so don't worry that the effort in killing the dragon is lost.

Please note that you need to discover additional shouts if you have learned/activated all your current words, this way you can use your saved dragon souls on the new words of the new shouts.

Shouts are discovered on the walls of old ruins, and gained by slaying and absorbing the souls of dragons. As more are slain the users ability to learn and use new shouts increases.

— Wikia - Elder Scrolls V: Skyrim - Dragon Shouts

In order to learn new shouts, you need to find all these word walls; you can get a quest to the next:

Although finding word walls can be very challenging try and use shouts in major cities. Whenever you do this you should receive a note from a courier which tells you "a note for your hands only" this note starts a quest to find a source of power and the current location of the next word wall.

— Wikia - Elder Scrolls V: Skyrim - Word Wall (Contains more details on all the locations)

To actually learn a new shout, once you have discovered the word wall and have a dragon soul to use, you need to manually activate it in the shouts menu. Select the shout and press the Activate button. It should be shown on your screen, but I believe the buttons are:

• R on PC

• X on Xbox

• □ on PS3

You have to spend the saved up dragon souls on unactive words to learn and activate them from the shouts submenu in the magic menu. I just found this out after being very confused also. On the pc this is done by highlighting the unactive shout and then pressing R. On the PS3, it is done with the Square button.

New shouts can be learned all over the world from finding word walls.

Dragon souls are absorbed and saved after killing a dragon.

To get some early new shouts you can ask the greybears for a few word wall locations, it will start up a small quest.