Let's go to the option Sizes on the menu Settings, a first screen appears: Size chart. On this screen, we can view the currently existing sizes and search for them using the 'Description' tool.

If what we want is to create a new Size Chart we will select the option New Table. A size chart screen will appear where we can name the table and add the sizes we want.

If we want to create new sizes within a size chart, we will select the new size option and name it.