I tried my first project with Arduino Uno. But I can't upload any code. Power green LED is working and orange LED is always on, not blinking, and IC also getting hot. What can I do to fix this problem?
My suggestion is to find someone else with an arduino, and get them to test (with their computer, known to be working) uploading to your Arduino. That way, you can tell if the problem is with your computer or the Arduino.
You haven't mentioned what your first project was. The most common mistake #1 is to light up an LED without a resistor. If you do that for a split second, you might (OR MIGHT NOT!) get away with it. If you leave it running for a few seconds, you are almost certainly going to burn out your AtMega (the IC on the board). This might very well result in the symptoms you describe. If this has happened, and your chip (IC) is removable (some are, some aren't), you should be able to buy a new chip of the same kind. An Arduino Uno has an AtMega 328, you will want a DIP package (they are the removable ones), and you will want one with an Arduino Bootloader pre-programmed. Replacing the chip may OR MAY NOT fix the problem. Make sure you note down the orientation of the broken chip before you pull it out - it will fit in, but won't work (and could burn out!) if you put it in the wrong way. There should be a little dimple at one end of the chip, right on the end. It should look like this (possibly without the pin labeling sticker): http://www.jaycar.co.nz/productView.asp?ID=ZZ8726&w=atmega328&form=KEYWORD
If your chip is not removable, or replacing the chip doesn't help, then you will need to get a new Arduino.