You are strongly advised to hire a lawyer to help you during the buying process. Your lawyer drafts and reviews contracts on your behalf and can explain all the legal and administrative issues you face. Your lawyer should also carry out any necessary due diligence (checking ownership claim of the seller, charges on the property, permits, etc.) and arrange all the required documents to complete the process (property registration, tax payments, etc)
If you do not have a Spanish solicitor or Asesoria, we can recommend a reputable local one for you, who speaks English.