Render quality

[Edgar Chevez]

Novice here

What is the best way to set a high resolution render quality image?  Please see both pics below.  One is what my render settings were.  If you zoom in on the rendered image, you'll notice it is a very grainy image (after about 400 passes).  I've seen many high quality rendered images posted here and don't know how to get same results.  Is there anything I am doing wrong or missing?

[Roy Hirshkowitz]

Your resolution is limited to 200000 pixels until you purchase a license.