which file would that be in?Im also not using the default theme, im using Symmetry

Where can I edit the button code?

Hello, So I need to change the 'Sold out' Button to 'Make an Enquiry' and send customers to another page I have made. I am using the Symmetry theme for reference.  This is how far I have currently got.I have edited the 'Sold out' Text to say 'Make an...