Alternating LED LTspice

Hello, I have to complete this task for a project:

This is the circuit I have implemented in LTspice so far:

My train of thought was that: when D1 is on, D2 should be off due to the CMOS inverter.
I am still very new to LTspice and I do not know how to check whether the diodes are ON or OFF accordingly. Moreover, I do not know how to check the voltage and current intensity on each diode (to check if the forward current is 20mA and the forward voltage is 3.6V).
What do you guys think of my circuit design? How can I check if I'm doing things correctly?

Apparently your "skills and knowledge gained so far" has a few missing items.

What is the input current for a MOSFET gate when on?
How will that light D1?

How much gate-source voltage does it take to turn the MOSFETs on and off?
How will the 1V input signal perform that function?

What determines that the current through D2 is 20mA?

To check your circuit, you run an LTspice transient analysis and look at the voltages and currents.