What is the best way to grow rosemary. My Friend has small shrub size plant , but hes deceased?

First start with a small plant, it will establish better than a bigger one. Make sure it isn’t potbound because herbs in pots often are and if it is, it will die in the first or second year. Then it needs two essential things, lots of sun and gritty soil. If your soil is heavy or tends to be wet, dig in a load of grit before you plant and put a big scoop under the roots. Plant in spring to give it a good chance to establish before the wet of the next winter.
I think your problem is either the wrong soil or not enough sun.

Rosemary comes from the Mediterranean, and grows in sandy soil with good drainage in full sun. It’s a good idea to put the plant on the south side of the house, and if it’s in a pot, don’t re-pot it. If it’s outside not in a pot, don’t water until in the summer if at all, and then, only in the evening after the sun goes down. Make sure the water is completely gone before you water again.

Since Rosemary is woody and an evergreen, it’s slower growing than other herbs. It will take many years with optimal conditions before getting it to the grand size your friend grew his to.

Don’t over water, put it in the sun, fertilize once a month Spring through Fall, and wait and see. Good luck, plants are finicky and not always easy to get going, but once they do and you get into a good rhythm of taking care of them, they can take off and become a wonderful part of your life.