Guilin Sun
Ansys Employee

There are several steps to design a metalens:

1: understand how does it work

2: know what the lens performace, eg a spherical or a cylinder wavefront

3: design the unit cell to create a phase change from 0 to pi or -pi to pi

4: test the whole metalens.

Please refer this article: https://optics.ansys.com/hc/en-us/articles/360042097313-Metalens

Duplicating other's results can be very challenge in many cases, since you may not be able to have all their design and simulation information. Please refer this post: 

Ansys Insight: Why my simulation result is different from published paper or experiment?

Since you are a bignner, please do this step by step, and write new posts for each question. I am sure you can quickly do your own design soon.