How to add a text to Word document with font color using C#

Question

I have a word document and I want to add some words to the end of it with font color using C#, any help ?

I tried to use the following code but it don't work 

 

doc1.Words[i].InsertAfter("Text to be added");
doc1.Words[i].Font.ColorIndex = WdColorIndex.wdBlue;