The template search will find all entries matching the criteria. For example, a search with a criteria of ‘Manhattan’ in the field named ‘Description’ (assuming there is one) would find any entries containing the substring ‘Manhattan’ in the ‘Description’ field.
If there are additional categories available underneath a category then there will be a clickable ‘plus’ icon shown to the left of it. Choose your selection by clicking the label (you will see it get highlighted). Hold the ctrl key to expand all child categories also.