Please correct this. This sentence I am going to say to my friend

You can say both sentences, but I would probably use; we are going to have a terrible time.

which one is correct please suggest me . and please explain why they are not correct? Tell me how could I tell this sentence in advanced way.

Please correct this. This sentence I am going to say to my friend

Please correct this so I can say it to my friend./Please correct this because I want to say this to my friend. 

Question: Are we going to have a terrible time tomorrow? / Tomorrow, will we have a terrible time? / Will it be terrible tomorrow? 

Statement: We are going to have a terrible time tomorrow. / Tomorrow, we will have a terrible time. / It will be terrible tomorrow. 

which one is correct please suggest me . and please explain why they are not correct? Tell me how could I tell this sentence in advanced way.

Which one is correct? Please give me suggestions and please explain why they are not correct. Tell me a more advanced example of this sentence. 

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When something is a statement, it may be confusing to add a question mark :) Both are fine without the question mark if you aren't asking a question. 

Something more 'advanced'/'natural': 

"Tomorrow's exam is going to be such a drag"

"I'm dreading tomorrow/tomorrow's exam"/"I'm dreading the exam tomorrow"