Add a donation option to pay by check

I also need to add a donation option to the area in my form where the option is to pay by check at the door. How would I add it there?

You can add the pay by Check option using the method described on the user guide:

How to Set up PayPal Along with Other Payment Options

Basically you just need Show/Hide Conditions to show the Check payment if the payment option selected is by Check.

Let us know if you are not able to do it.

I already have the pay by check option set up in my form, and just want to add a donation option there, so that when someone chooses to pay by check and is directed to the field where they choose their membership rate, they can add a donation. Then I want the "amount due at the door" to add the scholarship donation. Is there a way to do that?

I think you would need to perform some calculations to get the total on the form for an option to pay by check. Please use the following guide: How-to-Perform-Form-Calculation-Using-a-Widget