how do i configure my 3g usb to work on my mikrotik cpu
First, your 3g usb modem must support by MT.
When you plug the modem to usb port, you can find a new port (we asume it is usb2).
In winbox-interface menu:1,creat a ppp-client 2,change to advance mode 3,choose the correct port(usb2) 3,fill the Phone, user and password, perhaps in some case you need to fill APN 4,enable the ppp-client