The layout you presents looks like a PCell.

PCell is a complete, parameterized cells. It contains all the necessary masks. The n-well as well. But you need to add contact to n-well. Try Create->Via ... option.

Please have a look at this video:

https://www.youtube.com/watch?v=DPCu822wXPQ

Dear Haziq Rohail ,

Starting from the p-substrate you have at first produce the n-well by diffusion. After that you have to define the active area by local oxide LOCOS which isolates the transistors from each other. After which you produce the transistors.

As said before there are lay out rules which may be universal lambda based rules

or micrometer based rules. The rules are contained in the process technology file

of certain technology generation.

For more information about physical layout of integrated circuits please follow the book of VLSI Design Techniques for Analog and Digital Circuits, by Noel R. Strader, Phillip E. Allen, and Randall L. Geiger

You will learn how make circuit and physical design of ICs.

Best wishes