Inpage is very popular and powerful software. Inpage uses several kinds of keyboard for typing Urdu. Inpage also has keyboards for typing other regional languages of Indian sub continent.
To Switch between Urdu and English Typing Press CTRL+SPACE. Pressing the CTRL+SPACE again would shift keyboard back to original position.
Most people prefer Phonetic Urdu keyboard for typing Urdu in Inpage.
If you need help in using Urdu Keyboard For Inpage then please ask in comments here. I would answer them as quickly as possible