point to cpanel from another dns managment

Hi. my domain dns still manage in the old place. i have an a record point to the cpanel server. i guess i had to change the mx record too? is it true? if so. what exactly should i put in the mx name? and value? I would be very grateful if it is possible to be precise, it will also benefit everyone and it also takes time to see the changes, so it is advisable not to make a mistake :) Are there any other things worth defining at this point in the email? If so how?