Hey Eminem!
Good to see you at the forums, When your in the game type /buy 1 and it will provide you with a link you can click. Just follow that link through to paypal and your all good!
There is no direct link because each of the links is customised to the person making the donation, so that it makes sure it can give you all your stuff for donating. Also so that it ensures you are actually online on the server so that it doesn't have any trouble putting the items into your inventory.