Open the bridge widget that is on this page by pressing the Bridge button.
When prompted, select your wallet and sign into it.
Select the amount of SAND on the Ethereum network that you want to bridge to mSAND on the Polygon network. And then confirm the transaction.
Here is a video guide showing how to bridge SAND/mSAND.
It includes automatic captions for the hard of hearing or non-English speakers.
If you do not get a prompt from your wallet asking you to confirm the transaction, disable all adblocking and pop-up blocking extensions on your browser temporarily, and try again.
If there is still no wallet prompt, then try a different browser. Particularly if you are using Brave, which our The Sandbox community members report doesn't always behave nicely with non-Brave wallets.
It can take ten minutes, or sometimes more, for the mSAND to appear in your wallet. This can be affected by congestion on the network.
You need to use PolygonScan when tracking transactions on the Polygon network, not Etherscan, which is for transactions on the Ethereum network.