Of course, you need to purchase crypto to be able to fund your wallet, and we'd recommend you buy MATIC, as it's the native token for Polygon. Once you purchase on an exchange, transfer to your wallet address. NOTE about COINBASE, that if you buy MATIC there and transfer it, it will show up on ETH Main, and you'll have to bridge. We'll cover bridging in a moment. Here is @0xRobboTheGreg | XOLO with a video he made on buying MATIC and moving it in. Converting MATIC to WETH is easy and cheap, which is the reason we recommend doing that.