From what I can see, the website you shared above does not allow file upload to create the custom sign, only font selection and custom text.
I'd suggest trying other options where you see the option to upload a file (the images above will be enough). Ask for a quote and get an idea first:
customneon.com/upload-image
lamomoneon.com/products/customize-neon-sign
neonpartys.com/pages/upload-your-image-logo
crazyneon.com/pages/upload-your-logo
From my experience, and if you have time, in this case it is better finding custom neon shops in your area and going in person to talk with someone and get the best results. Same approach: get various quotes and select the one that makes you feel your gut more comfortable.
From what I can see, the website you shared above does not allow file upload to create the custom sign, only font selection and custom text.
I'd suggest trying other options where you see the option to upload a file (the images above will be enough). Ask for a quote and get an idea first:
From my experience, and if you have time, in this case it is better finding custom neon shops in your area and going in person to talk with someone and get the best results. Same approach: get various quotes and select the one that makes you feel your gut more comfortable.