CheckBox value

Hi there,
I am newbie in wordpress….
I put one option checkbox in my form and need to know is it selected or no.
for example:

If checkbox=1 then go to the page X1
Else
go to the page Y1

How can I write this code and where should I put it. Please help step by step

Thanks.

https://www.ads-software.com/plugins/visual-form-builder/