Space Shuttle destroyer

Hi! I'm trying to make an Mk3 two-story passenger plane. Since I'm not very good at building with Mk3 parts, (Past planes backflipping on the runway) I really need some help with it. How can I stabilize it in the same time of it being able to take off? I appreciate all replies!

Thanks! really appreciate it!

Thanks @king of nowhere!

do I place it in my KSP game data folder? The Squad folder? Any replies would be appreciated

Thanks @James Kerman! Much appreciated!

I want to make a space station, not massive just a single launch, can anyone tell me what I need?

I am very interested in trying to find the original MechJeb mod, but everything I see is Mechjeb 2, if it still exists somewhere on the internet, please tell me. I really want to find the original mechjeb mod.