Haha... I had solve the problem! I seeks help from those who are fluent in French or other languages, which requires those accented letters too. And they replied me in really short time! They had sent me the website address which will explain this.
As a result, I knew that to get Ô i just got to press Alt+0212. Here are some of them....( too much of them, so I just publish some):
á Alt+0225; à Alt+0224; â Alt+0226; î Alt+0238; and...
If any of you wish to know more about it, just visit this site.