general thread for practicing question formatting!

[Monster-Three]

    function fund() public {
        require(msg.value.getConversionrate() >= MINIMUM_USD,"don'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.

Can someone tells me what's going on?

[Monster-Three]

    function fund() public payable {
        require(msg.value.getConversionrate() >= MINIMUM_USD,"don't send enough"); 
        funders.push(msg.sender);
        addressToAmountFunded [msg.sender] = msg.value;
    }

you should add a 'payable' on the tilte of the function name.