How to sync music to iPhone from iTunes?

Ok so i downloaded a album from the internet and now its in my music library but i can't get it to go to my iPhone I've tried sync it and then pressed the apply but nothing happens every time i got to that iTunes/music app on my iPhone it says no content i allowed my computer to trust my iPhone but i don't know what to do if anyone knows what to do please share. I'm also using a Mac for my computer.

Make sure that on the screen where it has your iPhones information (the sync screen) under the music tab you select enitre music library.

Neither iTunes, or your Cell phone, will allow you to put "illegally acquired" music on them.

Everything you BUY from the Apple Store is perfectly SYNCED, but nothing you PIRATE gets synced, ever.

And, when you bought your iPhone and signed up for iTunes, you did AGREE to these restrictions.