Help with prepaying estimated taxes

Hi, I just started doing some contractor jobs in addition to my W2 job in September, and I am looking into prepaying the estimated taxes before year’s end. I know that I need to pay the self-employment taxes and income taxes for my bracket.

I have set up my IRS online account and I found that in the paying estimated taxes option, it is a total number, not itemized. May I ask if this is normal and if I should just put in the sum of my self-employment taxes and income taxes? Thanks.