No it's simple.

mud.h

void bar(void);

mud.c

#include <stdio.h>
#include <dlfcn.h>
#include "mud.h"

typedef void (*foo_t)();

int main() {
  void* foo_lib = dlopen("./foo.so", RTLD_LAZY);
  foo_t foo = (foo_t) dlsym(foo_lib, "foo");
  bar();
  foo();
}

void bar(void) {
  printf("bar\n");
}

foo.c

#include <stdio.h>
#include "mud.h"

int foo() {
  printf("foo\n");
  bar();
}

makefile

all: mud.exe foo.so 

mud.exe: mud.o 
	gcc -Wl,–export-all-symbols -Wl,–out-implib=libmud.a -o $@ $^
	
foo.so: foo.o 
	gcc -shared -o $@ $^ -L./ -lmud

.c.o: 
	gcc -c $*.c -o $*.o

Aside: Always post warning and error messages when you request help.