添加一个用于创建文章的附加字段（Joomla）？

I would like to expand the standard component for creating a new article (com_content) in Joomla with an additional field. I did an template override and added the field in the UI. But I do not know how I can add the value to the database. Which file do I have to change? Is this possible with an template override?I would like to expand the standard component f