There are a few ways to show a connection between your HubPages account and your twitter account.
Twitter - include your HubPages link on your twitter profile (edit profile)
HubPages - include your twitter link on your HubPages profile (edit profile)
If you want to share a hub from HubPages on Twitter - simply click the 'share' button above the comment box of a hub and click twitter. Fill in the status and send.
If you want your hubs to automatically tweet you might want to consider something like twitterfeed.com or one of the others. Beware of spam. Hope this helps.