Ribbon Workbench question here about creating command

I have a question about configuring a new command within the Ribbon Workbench.

I am trying to grab a URL address from within a single text box URL.

I have went through some online tutorials where it helps a user define a new command to an extermal URL, but I need to grab the url from a single text box url type field, which is located on the same entity as I am creating the button. https://ribbonworkbench.uservoice.com/knowledgebase/articles/71374-1-getting-started-with-the-ribbon-workbench#Defining_a_Button_Command

Please help, this is urgent for me!