What is WETH?
WETH (Wrapped ETH) allows users to make pre-authorized bids that can be fulfilled at a later date without any further action from the bidder.
ETH and WETH are worth exactly the same and can be exchanged on your profile.
Exchanging ETH for WETH on OpenSea
Click the wallet icon on the top right corner of your OpenSea page.
A smaller window will pop up asking how much ETH you'd like to convert to WETH.
Then, select the "Convert tokens" button as pictured below.
A MetaMask window will appear, asking you to sign the transaction.
Once successful, WETH will appear in the wallet portion of your OpenSea account. You'll be able to clearly see the difference between WETH and ETH, as WETH has a pink Ethereum diamond logo.