deals of the day

I have done it but still doesn't understand. in documentation there was shown that i must write a day in module and than in the product. I cant understand the difference.

Thanks for reply, i found the solution - went through the documentation what I couldn't understand is:
1. I need the discount module (which i have thorough your theme)
2. I must configure the concrete product AVALIABLE FROM:... TO:...

I can't understand the relationship between the module and the product. It only worked when I have written the date in module (as I understand it means - till what time the discount is available) and also in product page filled the two inputs from:... and to:....

for example is it right, how i guess:
I can write in module that the discount is available till 2019, so on my page always is shown the module.
and in concrete products which date i give from/till the date will this concrete product available. if i leave the input fields empty on the page will be shown that currently no deals?

I am interested in relationship between those module and the product page.

thanks :)