It depends what you mean. Is the class happening now or in the future? Is the action recurring? Is the class in a high school or online as an adult? e.g. I'm having/ taking English classes/ lessons at the moment. (recurring) e.g. I can't come to your party because I have an English lesson. (in the future) e.g. What's your next class? I have English. What about you? (in high school) e.g. What language are you learning? I'm having/ taking English lessons on iTalki. I hope this is helpful. Teacher Clare.