After I installed Kali Linux, I was using it as root and downloaded and installed many applications such as netbeans, xampp and more... But then after I created a normal user. When I log in with this normal user I cannot access my installed programs. What should I do in order to use a program installed as root in a standard account?
You need to update your PATH variable. You can do that in .bashrc:
Basically when you run program, $PATH is where it will be searched(path is list of directories separated by : ). If it can't find it there, you get an error message - which is your case.
I added most popular locations, but you might have installed your applications in different directories; in that case, simply change string that I provided accordingly.