How do I add a customer input field to the attributes of a product?

[lynkep1]

A few of the items in my store require customer input after they make a selection, but I cannot find how to add this as an attribute to a product as it is not required on all products.

 

For example, Name Mug, options are insert design, name required, etc

 

I have been able to set the attributes for the inserts, but I cannot work out how to add the field for the customer to input the name required.

 

Any help please? I am not very familair with php coding and has taken me 3 days with the help of other forum topics and my host provider to get the shop working properly so I don't want to muck it up now as I have added most of the products in already.

 

Thanks

Lyn.