Two different places I sell

I have an Etsy shop which I declared on my tax return but I also sell on eBay. Most of the stuff I sell is my own personal stuff that I’m just selling on, not bought to gain a profit but since Etsy is being so rubbish I have put some of my listings on ebay and sold one. So now I need to declare that too. How do I add it to my tax return as it was specifically for my Etsy shop that I did one last time so how do I put it as a separate thing?

Hi

Where your sell goods that you acquired to make a profit, this is declared as self employment income.  
If you dispose of personal possessions and their disposal results in a gain, then the gain is reported and is taxable as a capital gain.  
Have a look at the guidance at Capital Gains Tax: what you pay it on, rates and allowances.

Thank you