You really should not be using the classic template because in an upgrade you will loose all customizations made.

Read the template file section of this
https://www.zen-cart.com/tutorials/i...hp?article=230
https://www.zen-cart.com/tutorials/i...hp?article=143
https://www.zen-cart.com/tutorials/index.php?article=36

Other template tutorials
https://www.zen-cart.com/tutorials/i...hp?article=346
https://www.zen-cart.com/tutorials/i...hp?article=232
https://www.zen-cart.com/tutorials/i...hp?article=142