how to access two function programs from main program

"how to access two function programs from main program"

Note that you have only one program.
That one program consists of three functions - main, fun1, and fun2.
Presumably, these three functions are implemented in three separate files - say, main.c, fun1.c, and fun2.c?

As Hans-Bernhard says, if you really don't known how to call functions between separately-compiled files, then you need to do some basic 'C' textbook study.

However, if you just want to know how to do multi-file projects using the Keil tools, then you need to start by reading the uVision Getting Started Guide, and working through the example projects in it.

This will give you a proper introduction to the tools, how they work, and how to use them - rather than just jumping-in blindly at the deep end.

(The uVision Getting Started Guide is available on the 'Books' tab in the 'Project' Window; The 'Books' window is also available via the 'Help' menu; failing all that, search for GS51.PDF in your Keil folder)

"how to access two function programs from main program"

Note that you have only one program.
That one program consists of three functions - main, fun1, and fun2.
Presumably, these three functions are implemented in three separate files - say, main.c, fun1.c, and fun2.c?

As Hans-Bernhard says, if you really don't known how to call functions between separately-compiled files, then you need to do some basic 'C' textbook study.

However, if you just want to know how to do multi-file projects using the Keil tools, then you need to start by reading the uVision Getting Started Guide, and working through the example projects in it.

This will give you a proper introduction to the tools, how they work, and how to use them - rather than just jumping-in blindly at the deep end.

(The uVision Getting Started Guide is available on the 'Books' tab in the 'Project' Window; The 'Books' window is also available via the 'Help' menu; failing all that, search for GS51.PDF in your Keil folder)