There are a number of Spanish taxes to concern you:-
(1) Wealth Tax - which is based on your net (of mortgage and loans) assets in Spain. However Residents get certain exemptions in respect of their main residence
(2) Property Owners income tax
Both the above are very easy to calculate - your Spanish bank may even have the computer programme set up by the Spanish tax authorities to help you with your submission. Alternatively get a copy of David Searls book 'You and the Law in Spain' - published by Santana Books of Fuengirola. However before you can pay these you need receipted copies of your most recent IBI invoice (see below)
(3) IBI and Basura - the garbage collection - (your rates - payable to the local town hall 'Ayaumiento'). If you are having a problem with this go to the Foreigners Department in the town hall for help.
If you have a Gestor or Abogado do this for you they will charge about 150euros for this service. Remember that both husband and wife must complete individual returns.
I hope this will be of some help to you.