You could adjust the margin property – the first variable (0) is the vertical axis. So if you wanted to move the menu down then give it a positive value say 20px. If it’s something else than a screenshot could help.
Regarding CSS – the order in which you add CSS doesn’t matter. But beware if you have some broken code in the list, it will block any code below it, good way to test when something isn’t working is to add the code to the very top of the stack. Other than that just keep related codes together and in a order that suits you.