Here are three video tutorials from different makers showing you how to sew your own cloth serviettes or napkins.
The first from the Crafty Gemini is the perfect Cloth Napkins with Mitered Corners
Next is Napkins with Fringed Edges from Cucicucicoo
https://youtu.be/N0Vtf8EeVeE
and lastly how to make Double Sided Serviettes from Crafty for Home
https://youtu.be/Zvv5ctzc4zE