For my Spanish speaking classes I found this website that I will be recommending to the students.
I explored it and found it easy to navigate as it provides the basic tools for the Spanish speaking student. The website http://www.chino-china.com/metodo is organized in 40 lessons that take the learner from the beginning sounds with clear explanations. Is particularly useful for the bilingual (Spanish / English) speaker as it refers to the sounds of phonetics in both languages to compare and to help them accommodate to the mandarin phonetics. It also contains the audio component to help the learner hear the sound of words and eventually sentences. As with any free program online, this website will try to sell something, but I will advice my students to just explore the freebies and then later consider if there is the need for them purchasing anything.