Simply enter the details in the text box next to each custom field. All custom fields are optional, so, you enter details only for those that you need.
The count displayed against the name of each custom field is the number of characters you entered in the corresponding textbox.
The screen shot below is showing all custom fields (of type "Products") created so far as no custom field group is selected.
However, many a times, you only wish to enter details only for a small subset of the custom fields, in such a case, you can select a group (that you created previously) and the editor will only display the custom fields within that group.
In the example screen shot below, the group "Finishing" is selected, thus, the editor is showing one custom field that was in that group.
