Unlike "kindle for windows", for Windows 8 metro version of kindle app where is no "My Kindle Content" folder where i can place my own PDF files. Is it any way i can upload my own PDF file to it? I'm using Windows 8 Pro, not an RT.
According to Amazon, no. Look at http://www.amazon.com/gp/help/customer/display.html?nodeId=200939480. The last entry is:
Are Personal Documents supported?
Sending Personal Documents to Kindle for Windows 8 is not currently supported.
So no, sorry to have to tell you that, however the phrasing suggests that eventually, maybe.