Im not a native chinese speaker so im probably wrong also but i think it should be 我跟你想要练习中文，我可以帮助你练习西班牙文

我想跟你练习中文，同时我可以跟你一起练习西班牙文。 I would like to practice Mandarin with you, and you could practice Spanish with me.

Hi, I'm a native traditional chinese speaker. manybuddies is right and the sentence he suggest is actually better and more native.

Thank you so much!

Ok, disclaimer, 1. I'm not native. 2. I can't read traditional Chinese. Now, back to the subject at hand... 我想(要)跟你练习中文和帮助你练习西班牙文。 Although the grammar isn't too bad, I'm not sure exactly what you're trying to convey. This might be better: 我想跟你学中文，一起练习口语。同时，我也可以帮助你学习西班牙语。 I'd like to learn and practice Chinese with you. I could help you with your Spanish. ps: Chris' answer is wrong. Your sentence is still understandable, just not clear enough. His statement is just wrong.