So, I have tried this: Arduino Playground - HomePage
but did you notice it has like a buzzilion errors!?
Yes, I have. No, it didn't. Post YOUR code, and (some of) the buzzilion errors if you expect help.
After I've corrected the code and tryied again, however, it isn't connecting, I mean, it's not assigning the arduino port name to the variable!
Bummer. What variable?
Did I miss anything here?
Obviously. More than one thing, likely.
Is there another handshake?
Yes, there is a secret handshake. Someday, we'll teach it to you.
Can you guys please help me?
With what? You haven't posted any code, defined which Arduino you are using, or what you need help with.
ps. please do not say:"why won't you connect manually?" Because everytime I am pluging off and in my board it has another port name. And I am using multiple computers, too.
Well, I am going to say that. What I do is provide a drop down list to let the user select the port that the Arduino is attached to. You could, too.
If you want the C# application to select the correct port itself, AFTER you know that communications work, you are free to add that. But, don't make that the FIRST thing you do.