Is it a Catholic wedding? If so they don't usually do the unity candle in Spain, we had to ask for it.
I used a nuptial mass from the internet to do my order of service so that might be helpful so you know what goes on.
Also if it's a Catholic wedding there are set vows that you take, I think there are 3 versions to choose from.
Another Spanish tradition, usually in church weddings, is called giving the 'Arras'. You let gold coins fall into your new husbands hands and he does the same to you to signify that you will be sharing all worldly possessions from now on. We didn't do this because we have been sharing everything for a long time now and the gold coins cost 100 euro which was out of our budget!!