Firstly, don’t apologise for having bad English.
So, you need to ask if there’s a class tomorrow.
You’re going to make a question with “to be” in Present Simple.
The most important verb in the English language the verb “to be”, you’d be wise to master it.
Remember, in the present simple tense we invert the subject and verb from statement to question.
There is a class tomorrow (statement)
Is there a class tomorrow? (question)
If you would like more help with this or more, sign up for a trial lesson and I’d be pleased to help.