How do I start a sticker album?

You can put stickers in your sticker album yourself for 10,000 sP per sticker by using the Hustler in Pina Park or you can have a friend or another user put stickers in your collection for free. :)

[Edit] Or you can participate in the "Slap a sticker on the person above you" threads in the Achievement forum to build up your collection.

I was wondering this myself! Thanks

You're welcome! :)