Need Option To View Larger VIEWER of Images From Slideshows

Hello,

We are using slideshows on our website. But how can we view the images at a larger viewing size to scroll through? I want it where once the user clickson one of the thumbnail pics this ALLOWS A NEW LARGER VIEW SCROLLING THROUGH IMAGES VIEWER TO POP UP for viewng through images at a larger size?

Please advise ASAP as we are building a site and need this feture before we go live with the website.

Thanks,