Melting point for Mg:660C, Zn:410, Al:660 but I am tyring yo make an alloy of these elements with the percentage of %5Al, %3Mg and Zinc will be balance.
the melting point of alloys depends on its composition. Take a look on binary and ternary phase diagrams to find the melting point of the alloy you are aimnig for. E.g. the eutectic of the Zn-Al-system is 382°C at 95%Zn - 5%Al. To produce ZnAlMg you could start melting Zn or better a ZnAl pre-alloy and then add subsequently Mg or MgAl-alloy.
The creation of ZnAlMg alloys is nothing to be explained in some sentences. My advise: learn more about the background of binary and ternary systems, think about the system you want to create (amount of Al and Mg, which strongly influences the operating temperature) and then start your own process. This will take time. It´s nothing to be done or learned quickly.