How can I add a custom message bar to my product page?

Hi, pretty new to this whole thing!

Am I able to add in a message bar, so instead of doing a drop down menu for them to have an option on a product colour etc, id like a menu for a message as I have customised products so someone can add a name to it, a long those lines..? I hope this makes sense, could please someone help me with this.

Apologies, I am not fully understanding. Do you mean something like a personalised field? i.e if someone was offering free engraving on a watch, there would be a field on the product page that asked what text they want to be added onto the watch?