To upload NFT (non-fungible token) items on an upstairs marketplace, you will typically need to follow these steps:

1. Create an account on the marketplace platform.
2. Verify your identity by providing personal information and proof of address.
3. Connect a digital wallet that supports NFTs, such as MetaMask, to your account.
4. Create or acquire the NFT item you wish to upload. This can be done using a tool like OpenSea or Rarible.
5. Use the marketplace’s upload feature to submit your NFT item for sale. You will need to provide information such as the item’s name, description, and price.
6. Wait for the marketplace to review and approve your listing.

Note that the steps may vary depending on the marketplace platform you choose, so it’s a good idea to check the platform’s help center or FAQs for specific instructions.