I have seen this tutorial before I came here.
my problem.
1) yaourt is for Arch Linux, I installed xbindkeys using sudo apt-get install… command.
2) I ran xev before, unfortunately it didn’t recognize back and forward buttons as button 8 and 9 as shown in the tutorial… I always try to google the answers and figure things out by myself before i go to forums to ask for answers, i am stuck that’s why I came here to ask… 
When I press left mouse button, it shows this.
ButtonRelease event, serial 34, synthetic NO, window 0x4400001,
root 0x18c, subw 0x0, time 2588878, (155,8), root:(205,128),
state 0x100, button 1, same_screen YES
when I press BACK button on the side of the mouse, it shows this.
EnterNotify event, serial 34, synthetic NO, window 0x4400001,
root 0x18c, subw 0x0, time 2590416, (155,8), root:(205,128),
mode NotifyUngrab, detail NotifyAncestor, same_screen YES,
focus YES, state 0
KeymapNotify event, serial 34, synthetic NO, window 0x0,
keys: 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0