In the "Save Clip" window you can choose a name for the new clip, select a topic from the list of existing topics or create a new topic (by clicking a topic name in the "Create new topic" input.)

The small-scale image of the selected topic page enables you to determine the initial position of the clip. Simply drag the red rectangle to position it on the topic area. If you uncheck the "Save as icon" checkbox, the clip will be saved in its original size. Otherwise it will be saved as an icon.