How do hair extensions work?

My hair isn't layered and I want to try to tease. Will it work if it's not layered?

ok I have straight hair extensions and my hair is wavy how can I make my hair extension wavy also?

does that aussie lotion for hair really work? it claims to make hair stronger and full of life

I bought some Oceana's clip in hair extensions, they're 100% human hair, I dont know if they're virgin or not.

Where do you buy hair extensions? I don;t wann buy them online. How muich do they cost?

How can I mend split ends on my clip in hair extensions?!?!?! its so irritating.

I'm wondering because i have naturally wavy hair. Thanks in advance!

I want to dye my hair and the extensions also but I dont know how long you have to wait to put in extensions after you die yo...

Do you guys think the in styler hair straightner works? Have you used it?

Ok I really want some hair extensions. I'm going for the scene look where they have short hair at the top and long at the bot...