How to add a custom text field in the 'add to cart' option?

Hi, I am really struggling to find a way of using the Quick add to cart’ function on my shopify website on personalised products. When the customer clicks ‘add to cart’ it doesn’t give the customer the option to enter their pet name for the personalised products i offer or even the choice to select a different font Colour. Now I know how to get around the font colours by adding these as an option on the product page however I am struggling to work out how to add a text box that will appear when the customer clicks ‘add to cart’ without having to click 'full details ’