If I’ve understood you correctly, you want to put links on your page that will call content into a frame rather than open another page. If that is correct, it can be done, but it’s a bit tricky.
Basically, you add an iframe to your page with code such as:
You can add dimensions and styling also so that the frame is of a specific size with or without borders etc…
Next, you would create your content on individual pages of your website (all excluded from navigation) Each page should be sized to the same dimensions of your iFrame.
Unfortunately, Sparkle doesn’t include an onclick event for links and buttons where you can specify a page or url and a target. So, you will have to create your links by adding embed codes such as this
<a href="1st-page.html" target="myiframe">Description of the first link</a>
<a href="2nd-page.html" target="myiframe">Description of second link</a>
<a href="3rd-page.html" target="myiframe">Description of third link</a>
You may have to style your links by adding some CSS to the code window between style tags.
When any of the links are clicked, the relevant page will display inside the iframe.
It’s not an ideal solution because you won’t be able to preview the result in Sparkle. You’ll have to publish to disk to see it working.