What to do esp in Debugging

so , I will to Understand debugging , i am very new and I am not a IT student.. .I am since Three Days this exercise to Understand , but without sucess...

I working with Linux and the Program GDB:

1 #include <string.h>
2 #include <stdio.h>
3
4 void overflowed() {
5 printf("%s\n", "Execution Hijacked");
6 }
7
8 void function1(char *str){
9 char buffer[5];
10 strcpy(buffer, str); (**3**)
11 } (**2**)
12 void main(int argc, char *argv[])
13 {
14 function1(argv[1]); (**1**)
15 printf("%s\n", "Executed normally");
16 }

The Number 1 , 2 , 3 are the Program Break Punkt .

(gdb) break 14
Breakpoint 1 at 0x8048433: file overflowtest.c, line 14.
(gdb) break 10
Breakpoint 2 at 0x804840e: file overflowtest.c, line 10.
(gdb) break 11
Breakpoint 3 at 0x8048420: file overflowtest.c, line 11.

Break the line 14,10 and 11 .

than with run to given Four A

(gdb) run AAAA
Starting program: /home/georgia/overflowtest AAAA

Breakpoint 1, main (argc=2, argv=0xbfb73004) at overflowtest.c:14
14      function(argv[1]);

than with x/16xw $esp to my First Break ,line 14 , i come

 (gdb) x/16xw $esp
 0xbfb72f50: 0xb77e6ff4 0x08049ff4  0xbfb72f78  0x08048489
 0xbfb72f60: 0xb780a7b0 0xbfb72f80  0xbfb72fd8  0xb769e775
 0xbfb72f70: 0x08048470 0x08048340  0xbfb72fd8  0xb769e775
 0xbfb72f80: 0x00000002 0xbfb73004  0xbfb73010  0xb77fab40

so, i to search to Understand , what on the far left is 0xbfb72f50: and all Hex back from it come, his meaning.... . Can Please anybody help me with easy Words explain , to describe it ? , Very Thanks!

The first column is the address, that is, on the first line, the value of the %esp register.

For an explanation of the stack pointer (%esp) and stack frame (%ebp) registers, consult a text on compiler construction, such as chapter 6, Activation Records, in Appel's Modern compiler implementation in ML. Relevant keywords are activation records and stack frames. Wikipedia has some basic information, too.