Upgrade routeros

i m hacing routerboard rb433
it has os 3.15

but i want to upgrade it to 4.16

how i can do it pls explain in detail cause i m new to mikrotik

rb 433 have level 4

drag this file to the Winbox FILES menu: http://download.mikrotik.com/routeros-mipsbe-4.16.npk

reboot router. That’s all



but it show cannot change the key

because you didn’t follow the instructions! drag it to the files menu, not packages menu.

i do it

but when i reboot routerboard now its not shown in winbox
pls help me what i will do