My project was to make 2bit array multiplier using 10 mosfet full adder.  Since I was a beginner, I choose a simple circuit.
I searched everything about my circuit in google. Then I got some research paers related to this.
Next was to implement it using esim . 
Using kicad schematic was drawn.
After adding PMOS , NMOS library esim worked properly and gave correct output.  
Next was to install zip files of sky130 and implement using ngspice. This was the biggest task for me. 
I was not getting the write output.
To get the proper output I did these steps

Step1 :
Added library file .lib "models/sky130.lib.spice" tt

Step2:
Then I added 'x' before each mosfet M1,M2,M3 and so on.

Step3:
I customized w/L ratios for each CMOS and NMOS.

Step4:
Replaced PMOS with sky130_fd_pr__pfet_01v8 and NMOS with sky130_fd_pr__nfet_01v8

Steo5:
At last added proper input votage , pulse voltage , time period etc.

Then finally I got exact result by skywater 130 pdk.
