Controlling popup for link on icon

Hi,

I am working on a facebook share function, that will open a facebook share dialog when clicking on a link.

I have made an icon list, where one of the icons has a link that opens the share dialog when clicked.

However, I cannot figure out where to edit the settings for this link, so I can make it open in a custom sized popup, the standard options let me choose between a full new window, or the same window.

Is there a way that I can add styling to the link, so that it serves as a sharing button with a controlled sized popup dialogue?