It is very easy to do that when you have written your hub to be published on hubpages, you can add a link in the body of the article or hub by opening up the text widget of your hubpage and selecting the specific word like "Google Adsense" using your mouse and clicking on the the fourth button from last which reads insert/edit link and the sign on this button is of a CHAIN. A pop window will open up displaying two things:
1. Link URL: Paste your the url of the link you want to show as a word over here and also include http:// in the beginning if it is not there.
2. Target: Two options will be there: A. Open link in the same window and B. Open the link in a new window. Select whichever suits you.
Now press the insert button and click save on the text widget of your hubpage. click done editing. Click on that word and you will be directed to the url of the link your pasted.
I hope I am able to solve your query.