Use them and then you can learn the style to craft other gear. Motifs teach you the style...example: use argonian motif, and then you can craft in the argonian style at a crafting station, motifs only have to be used once and then you can craft that style indefinitely. I hope this helped!

Crafting motifs or pages from them are books which can be read (which consumes the item) to unlock the ability to craft items in that style.

For example if you read the Dark Elf motif it will unlock the ability to craft items in the style of Dark Elf.

Earlier books came as full books in Superior (blue) quality for regular races, Epic (purple) for Daedra, Barbaric, Primal and Ancient Elf and Legendary (gold) for Imperial.

Later motifs all come in single pages of Epic (purple) quality or full books of Legendary (gold) quality. Full books are very rare and often sell for more than all the pages would cost as collectors like to have them to show off.

If you're not interested in crafting you can sell these to players, as they vary in value. PC EU these can be as low as 200g or as high as 30k gold for the pages and most Legendary (gold) books going for 80k (Imperial) to hundreds of thousands (most others).