do this the easy way ..
plug your phone into the computer via micro usb
on your phone slide down your notification bar and touch the "USB CONNECTION"
touch on "USB MASS STORAGE"
on your computer go to "my computer" find your usb drive connection and open it
make a folder labled "music" [optional it will make a folder for you if you dont]
open up itunes
highlight and drag the music to the music folder
easy !! sounds like a lot but it's not .. you will get used to it 
don't forget to slide the notification bar down .. touch USB CONNECTION and touch charge only .. if you don't do that you wont see the music on the phone or play it.
another way which is bother some is to remove your battery .. take out your micro sd card .. put it in a adapter .. then put that in a usb card reader .. plug that into the computer and drag and drop like above .. even more steps .. the above steps are better ..
