General Thread for practicing question formatting!

[Maxhaufe17]

       function fund() public {


             require(msg.value.getConversionRate() >= MINIMUM_USD, 'Didnt 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 tell me whats going on?

[Maxhaufe17]

please add 'payable' keyword