Can someone please answer some questions about a 24hr urine catch?!

Abby

So I’m 11+3 and have to do a urine catch starting tomorrow due to borderline high BP. They literally told me nothing about it except that I need to flush my first morning urine and then start catching with the second urine.

What do I do if I fill the jug?

Do I catch the next morning urine if it’s still in the 24 hours?

Someone please help!