I'm not sure I understand the question, if there is one.
If you're asking how to plug it in, it's either the purple port on your front panel opposite of the headphone port, or the purple port on the rear of your computer. They're probably marked "Mic" or have a picture somewhere close. (mouse, I'm pretty sure that the orange port is one of your surround-speaker out ports. Maybe my motherboard's just different...)
If you're asking why it isn't working, check that it's plugged into the correct port, firstly. Then, make sure you have your recording and input sources set correctly in the Realtek panel, and in the control panel: Start > Control Panel > Hardware and Sound > Manage Audio Devices (under sound) > Recording.
If you're asking where to place your microphone, then you can figure that out for yourself by trying it.
Be sure to check that it's even being recognized, first, by going to your Realtek control panel and checking to see if the Mic port being used is lit up once it's plugged in.
I can't really explain it any clearer than that... that pretty much covers anything you could have meant by your lack of actual question posed...