Choose 'Preferences...' from the menu (also available in the dock menu). The 'General' tab has several options to control the behavior of SlashDock. The 'Sites' tab allows you to add/edit/remove Sites.

The easiest way to add a new Site is to enter the headline URL in the text field and click the '+' button - SlashDock will attempt to auto-configure this Site and populate as much information as possible in the Site list. You may also drag and drop a 'feed' URL onto the Sites table to autoconfigure it.

You can edit any Site setting by double-clicking on that setting in the Site list. A site can be 'disabled' by un-checking the box in the first column. If you have previously customized your Site configuration, you can automatically insert the Default Sites by clicking the '+ Default' button. You can also reorder the Sites by dragging and dropping them.