If you have a spreadsheet with your auction items you can upload all at once.
Step 1) From the All Items page, find the button that says "Upload Items in Bulk".
Step 2) Download the Sample File. Please Do Not edit Row 1, Delete, Rearrange or Rename any of the columns. If columns do not apply please leave blank.
If you want to upload items by category, you will need to load a sample file for each category.