How to set conditions in my form properly?

The question reads, will you attend the reception and dinner? If they say yes, how do I redirect them so they can select their dinner entre?

Another question will read, will you bring a guest, if they say yes, same thing, how do I redirect them so they can select the guest's dinner entre?

How do I add a pay by check option?

Certain attendees will not be required to pay a registration fee. How do I set up a fee waived code? 

If a registrant can't attend the conference but wants to send a substitute in their place, how do I go about setting up a substitute option?

This is how you could do that:

Add a condition that will show/hide each of the sections. For example:

I added several radio buttons and section collapse fields, based on what is selected in radio buttons will reveal appropriate sections:

And I achieved that by adding these conditions:

So if you will attend the dinner, the section choose entre will reveal, all you need to do is to add appropriate fields in that section. That counts for the Guest dinner section as well.

Regarding the payment and check, I did that by adding a Text field for mailing check instruction:

So if the check is selected show the Text, if the PayPal is selected show the PayPal field.

Regarding the Free option I added a coupon:

So you could give your users a code 100discount and the price will be zero for them.

Here is my test form https://form.jotformpro.com/71975171259970 feel free to check it out.

If you have any further questions please get back to us.

Thank you!