I'm not sure how you entered the image links originally but one possible way (without the need for any manual coding) would be as follows:
(1) Upload the image you want to use to the Library ('Library -> Upload').
(2) Create your page (where the link is going to go).
(3) Click the 'Image' button on the Showkase editor's toolbar (the first icon to the right of the bullet point icons).
(4) In the pop-up 'Image Properties' window, click the 'Browse library' button to select the image you want to use.
(5) Set the dimensions for the image (if necessary) on the 'Image Info' tab.
(6) Click the 'Link' tab and set the 'URL' and 'Target' for the link.
(7) Click 'OK'.
Alternatively, you could just click the 'Source' button on the Showkase editor's toolbar to enter source mode and type in the RAW html code for your image link which might look something like this:
<a href="/showkase/gallery/index.html" target="_self"><img src="/showkase/_library/files/img_0001.jpg" height="400" width="600" alt="image" /></a>
Would it matter if my Showkase-Pro build was out dated?
No. This wouldn't make a difference. Whatever you were able to do with your version of Showkase a year ago, you can still do now.
However, you might like to upgrade your site to the current version of Showkase (v1.3.6) by following the instructions here.
(Upgrades are free within the same major version number.)