Step 2: Install Urdu Phonetic Keyboard (v1.0)
Download and run Urdu Phonetic Keyboard Installer.
Windows Vista
If you are using Windows Vista, after installing the above keyboard you can type Urdu on your Windows Vista Computer. To switch between Urdu and English keyboard, you can press Alt+Shift. Or on your taskbar you can see EN or UR and click on it to select the language as shown in this figure:
Windows XP
If you are using Windows XP, you need to follow step 3 to enable Unicode Urdu in Windows.
Keyboard Layout
You can also download and print this Urdu Phonetic Keyboard Layout 
for your reference. This page explains which key has alef, bay, pay etc. Here is the low resolution image:
