This is a test of commonsense. Complete the next sentence:

How to make an ironing board cover from scratch
If your foam underneath is ripped or scruffy, you should replace that as well.
One thing that you can try is upholstery wadding underneath.
Untie the cord from underneath the existing cover (it is probably wrapped around a plastic toggle.
If it is, good, you have half of your materials already). Pull all the string out, and stretch the cover out flat.