Sample application will surely help you to learn this.
//If Flag is true, show the specified control else hide it
//controlToShowOrHide is the id of control you want to show hide
function ShowHide(Flag, controlToShowOrHide)
var row= document.getElementById(controlToShowOrHide);
Calling Above function
Calling more than one function at a time.
See above example, in OnClick event ShowHide function is called twice. same way you can use different function.