How to update iTunes without it wiping my library?

I'm trying to put my music onto my iPhone but when I plug the iPhone in it says I need the latest version of iTunes. I don't know how to do this in a way which will have my library transferred over to the new iTunes. I'm aware that downloading a newer version of iTunes doesn't delete the music files themselves but I don't want my library to be deleted/end up with a new blank iTunes, as I have too many songs to put on one by one and I'm not sure how to go about it using an external hard drive. Is there any simple way I can download the new iTunes and have my library transferred over? If I select help>check for updates in iTunes and then download the latest version, will this new version be blank or will my library automatically transfer over?

Your library does not change when you update the iTunes…

The update does not affect the library. Think about it. If it did who would use it?