For date fields that have std_date as their default visualization, you do not need to manually add them to your web page. Simply include your date fields in your web_map or in a list that is present in your web_map and they will be visualized using the date weblet. Similarly fields of type time and of type datetime will be visualized using the time (std_time) and datetime (std_datetime) weblets.
If you do need to add the date weblet to your page manually, simply drag the date field from the Fields tab onto your page. Alternatively, open the XSL for your webroutine in the LANSA Editor and follow these steps: