Where do I place the server .jar? I've placed it in the bin and it just reverts mc to 1.2.5
lol no. You don't put the server.jar into the mine craft folder. You create an entirely new folder for it. Then use a shell command to launch it. You can use a guy or not, but that's up to you. I don't, but like I said, that's my preference. If you end up using bukkit, you had to learn permission (mostly) yourself, you can find template and stuff around the clusterforget of the deep internet. But most of it you will end up learning yourself anyway.
Yeah...
1. Make a new folder, name it whatever you want.
2. Move the newest server.jar into it.
3. Create the shell command for it and put it in the same folder.
4. Run the shell command but double clicking it.
5. A whole bunch of lines will start scrolling through terminal's window, ignore them.
6. Eventually, when the have stopped being created, the server is done creating itself.
7. Shut it down, yes. Turn it off. Do not "close" it or "force-quit". Type "stop" and press "enter" .
8. When it says [Process completed] Then you can close the window/quit terminal.
9. Go back to the folder and you will see that quite a few files have been created.
10. Open up the file "server.properties" . If you get an error message saying unrecognized filetype then right click > get info. Find "Open With" and browse around for text edit.
11. In that file change whatever you want. If you do not know what some of them mean just ask.
Then, close it and start the server up again. If you need any over help don't hesitate to ask. I fell that I'm the only person who can/is willing to help with Macs.