The first word is DESIGN.
Take pencil and paper, not a computer.
The second word is THINK.
You probably need a database. What are the tables and their relationships? You probably need computer input and output. What are the hardware devices you need extra for that? You probably going to use VS C# as a OO tool. What classes do you have to develop?
What kind of hospital is it? The complexity of you design may depend on it.
Is it a military hospital?
A burn center?
An academic hospital?
A field hospital?
A maternity hospital?
And just as Sknake says, come back here if you have a more specific question.