Investors & landlords

i'm not skipping but i am very stressed. Unfortunately desktop isn't completely clear - at least to me on all this-even with step-by-step walkthroughs- I entered things like realtor commissions in the section circled in the attached screen shot - right? wrong? 

What is throwing me off - is under "Expenses" - a few steps later, TT refers to this as "[Enter] COMMON EXPENSES" and realtor commissions aren't common, are they? 

What is