You did very well, just some minor corrections for you:
I need more practice!
I decided to join italki because I'm learning English at college, but I've been a little bored in my English classes. In fact, I've noticed that I understand the majority of grammar structures but I can't express my ideas clearly. And I think if I get more practice I can express myself and speak better.
And of course, I'm going to help learners that want to know the Spanish language.
I hope you can help me with your corrections and have a nice day! :D