Simple. Find a specific word or phrase you'd like your readers to see and click on, then choose the "hyperlink" button in your edit box and choose which Hub you'd like to link to.
This creates a hyperlink that will take your readers to anywhere you choose in HubPages. You can do this as many times as you'd like, but if you're trying to rank your Hub on the search engines, don't over do it. 3-4 max!