I know this should be easy for me but I'm just getting my feet wet.

I work for a consulting firm so we all have multiple projects that we work on daily and have to log the hours spent per project.  Right now they are using an excel spreadsheet. 

I've set up the form and included a radio button that says "do you need to enter more time for another project"  Y/N

How do I set it up so if they say yes  the need fields pop up again.

Thank you in advance for your help.