Adding on what @pascal recommended, Customizing openmrs source code would be easy when you start from creating your first module this also depends on your need, because it gives you a basic mode of architecture of how openmrs as whole works around. Another option when specifically you want to create new forms with in openmrs REFF-APP , this can help you HTML FORM ENTRY REFERENCE thanks.
@rodatabc Great like i said before you customize openmrs source code, you need to first understand which openmrs modules does fit your need, Am very sure for your hospital customization there are some already functionalities you have pinned to customize to fit your needs in openmrs , Are you willing to explain more to us more of your basic functionalities you want to add in your hospital. This will give us a picture of which modules to point to. Take forexample if someone want to create or customize entry forms using openmrs, then we directly go for htmlFormEntry module. if someone wants to create reports, we directly switch to reporting-module. i hope it make some light overview
They are a bunch of alternative options to achieve your goals, I Would advise to list all possible ideas and functionalities once again you want to be able to achieve in your pharmacy ,You can use openmrs standalone application as whole because it comes with many different modules with different use case , If you are interested in building or customizing forms, either on registration page, home page or any other place in openmrs, there is alot for you. Have you taken a deep look ,or have you try running openmrs standalone and explore some of its functionalities whether they can be fit for you?
You main ideal is related to forms creating and customizing Forms, if that is so, openmrs was built behind the scenes for end user to be able to customize and built new forms on top of HTMLFORMENTRY module , this comes with openmrs standalone. Take a look at this How is pharmacy managed in OpenMRS