Sold items on Reverb and eBay as personal sales, but was not enough to meet reporting threshold. How do I enter this?

I casually sold personal items on Reverb and eBay, but did not meet the reporting threshold and thus did not receive a 1099-K for either site. However… "Even if you don't receive a 1099-K, or you make less than $5,000, you still need to report all taxable income to the IRS.” How would I enter this without a 1099-K? I have looked at entering a 1099-K and it does require a Filer name and TIN which I do not have without receiving a 1099-K. Should I enter this in a way not using the 1099-K? If so, how would I account for expenses like packaging, fees, etc? Would any of these personal sales need to be reported if these are at a loss?