Can i diploma from cs after that b.tech in cs then i can apply for job in app devloper and i want make own apps and how to come in market and need also graduate to make own apps and come in market for bussiness...

Why do you want to do diploma when you can do a B.Tech after 12th?  First concentrate on getting the degree and then gaining enough experience in creating or developing apps. As for business, that is not easy unless you have some experience. By the time, you complete your degree you will know how the market is and how best to move forward. It is very early right now to predict all of that. Trends change every year. So I would advise to get all the required knowledge and then everything will fall into place. All the best!