hi i got easy step for install software like ubuntu software center

oke lets do it

First edit your repository
Code:
nano /etc/apt/sources.list
deb http://http.kali.org/ /kali main contrib non-free
deb http://http.kali.org/ /wheezy main contrib non-free
save(ctrl+o) exit

second update the repository
Code:
apt-get update
third instal software center
Code:
apt-get install software-center
now you can run it on terminal with comand : sowtware-center , but i told u for make a shorcut in main menu

open Aplication> > Accesories > Main menu > klik new item in right place
type Name : Software center and Command : software-center ,
then ok

look aplications menu, you will found software center