General Thread for practicing question formatting!

[Khanhbroo]

    function fund() public
    {
        require(msg.value.getConversionRate() >= MINIMUM_USD, "Didn't send enough!");
        funders.push(msg.sender);
        addressToAmountFunded[msg.sender] += msg.value;
    }

On this function, I'm running into an error:

TypeError: "msg.value" and "callvalue()" can only be used in payable public functions. Make the function "payable" or use an internal function to avoid this error.
  --> contracts/FundMe.sol:31:17:
   |
31 |         require(msg.value.getConversionRate() >= MINIMUM_USD, "Didn't send enough!");
   |                 ^^^^^^^^^

Can someone tell me what's going on?