2 Wan => 2 Lan

Hi guys, im beginner with Mikrotik
i have internet connections from the same ISP and i want to separate them in 2 different switches.
so PORT1 is Wan and PORT3 is Lan (for ISP Line 1)
PORT2 is Wan and PORT4 is Lan (for ISP Line 2)
the problem that i have is that actually only one line is active and the other is passive on standby.
i need the to run both as the networks they broadcast are not the same.
plz any idea how to do this?