Firefox > Tools > Options > Content > [x] Load images automatically

Click "Exception" and check any website name is add in that list.

for more

• https://support.mozilla.org/en-US/kb/fix-problems-images-not-show

Do you mean uploading image to the eBay site to add them to your eBay website?

Make sure that your security (anti-virus) software isn't blocking this uploading.

Start Firefox in Safe Mode to check if one of the extensions (Firefox/Firefox/Tools > Add-ons > Extensions) or if hardware acceleration is causing the problem (switch to the DEFAULT theme: Firefox/Firefox/Tools > Add-ons > Appearance).

• Do NOT click the Reset button on the Safe Mode start window or otherwise make changes.

• https://support.mozilla.org/kb/Safe+Mode
• https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes