Word prediction using n-gram technique

Question

Hi all,

I have a list of most frequently used words in the english language (about 500). And a windows form with a text box where user types in whatever he want to. I have a radio button for word prediction which the user enables if word prediction is desired.


What I want to do :

 I would like to know a suitable approach to implement word prediciotn using the n-gram tehchnique. Do I need a database ? how do i compute the probabilities? Can anyone please help me with the approach?