You are going to mint USD cashu tokens by paying a lightning invoice from the mint using any cashu wallet that supports USD unit. For testing purposes, Please use the cashu wallet at https://wallet.cashu.me/
Copy the mint URL https://stablenut.umint.cash by going back to the home page and click the "Cashu wallet" button
Paste the mint url in the Add mint text box and click the plus button and then "Add Mint" button