Before minting and using vDOT you first need to hold DOT in the Bifrost network.
Prepare DOT on your wallet address on the relay chain:
Purchase DOT on CEX or DEX
Buy DOT with credit card with fiat on-ramp solutions (i.e Banxa)
Withdraw from other ecosystem parachains (Hydration, Moonbeam, Astar, Interlay...)
Login to app.bifrost.io and confirm the network in the upper right corner is Polkadot
Polkadot network selected
Click "Cross chain" in the main navigation menu on the left to enter the cross chain function
Cross chain menu
Click on the "From" option and select Polkadot
Cross chain interface
Enter the amount of DOT that needs to be crossed in into Bifrost, and click "Cross in" to complete the confirmation and sign the transaction. Finally wait for the transaction to be completed (6 to 12s).
You successfully deposited DOT on Bifrost !