There are two way:
1) find the program for your webcam, or
2) open another program that uses your webcam (like Skype)
You should always make sure that you have updated your BIOS, drivers, and software for your computer.
I don't know if the Aspire 5733 has a main program that can handle the updates but it's been my experience that you usually have to do it manually. There are ALWAYS updates but they usually slow down and disappear after two years from the laptop release date.
*Some drivers are not applicable as there may be different configurations such as different video cards. Make sure to get the correct ones. Again, check to see if there's a main update program and if so, that it works.