How to transfer music directly from computer-iphone, using itunes?

I have 1000+ songs i downloaded a folder today and i already have my old music in my library, i don't feel like sifting through thousands of songs to find the ones i don't have, so how do i get it to go directly through without having to do that?

You don't.

You can add everything to your iTunes library, and then ask iTunes to show you the duplicates. Then you can delete the duplicates.

The useful tip is to locate where is your library song installed - open i tunes library- music- right click and look for file location… Then copy and paste your new songs on the same file and windows will automatically show the duplicate songs and in one click windows will prevent copying them into same folder… After you finish restart itunes connect your iphone and after synchronization you are done

You can use 4Videosoft iPhone Transfer Platinum, it is professional in transferring music between computer and iPhone. And it is very easy to operate, you will finish your transfer process within several clicks. When connected the device to the software, you can choose the files you want to transfer. And one click on transfer, you are able to move your songs to the iPhone.