Transferring music from iPhone to Mac?

I've got a new macbook, and I want to get music from my iPhone onto my mac iTunes. I don't want to have to download anything, or do anything elaborate. As simple as possible instructions please

Unfortunately anything Apple does is very proprietary, but they make a heck of a good business doing it. I have a PC and wouldn't have the slightest idea, but I used to have an iPod so I may be able to give some kind of advice.
First, do you still have the iTunes account that contained all the music you have on your phone? Of so, you can hook up a USB drive to the computer with that iTunes, open it in (my computer? I use PC, sorry!), and then open your iTunes. Now you need to 'select all' in your music library. For me I would press Ctrl +A, but I suspect it would be different for Mac. Maybe right click one of them and see if 'select all' is there, or just left click the top song once, hold shift, and press the down key until they are all highlighted.

Now drag them into your flash drive (also make sure it has enough storage. If not, you may need a bigger one or will need to transfer them in separate groups, one at a time.)

After that you plug it into your macbook. Now do the opposite (flash drive to iTunes). If it doesn't work there should be a little arrow at the top of the itunes window facing up (if I recall). You click that once and it will allow you to add external files.

That is all I can suggest. If it still doesn't work I'm sure you can go into the iTunes store and they can explain everything.

Nothing complicated like Tyler trying to guess. You open up iTunes on Mac, connect phone via USB and iTunes do the rest, all music from phone will go straight on to mac.