Text from a textbox to a product description

[SylvesterAbreu]

Hi everyone.

A friend of mine has a web store at bigcartell(HTML,CSS,JavaScript) and needs an extra textbox (which can be created within div or form) on specific products where costumers can add their personalised message to the product.
I wonder how could I add this message to the order or product description when customer do their orders.
Any help with be very welcomed.

Thanks in advance