Beverly Jolly, b. 1946 in California

I am unfamiliar with trying to find adoption records, can someone help me?Trying to find Beverly Jolly b. abt 1946 and put into an orphans home in Los Angeles, CA.She was the daughter of Helen Lorraine Jolly and Robert Jolly.She had siblings:Carol Mahurin, Ronnie Mahurin, Betty Jolly and Charles Jolly who were put up for adoption in either Eugene or Sweethome, Oregon.Carol and Ronnie born 1939 and 1940 were found and reared by my grandparents Renald and Berta Montgomery Peterson.They were unable to take the younger children.Betty and Charles were adopted and have found our family.Their mother Helen Lorraine Jolly who was missing since about 1946 has been found recently.There has been a successful reunion.The only missing link is Beverly.
My mother, sister-in-law, to Helen Lorraine was pregnant at the same time (1946) when Helen Lorraine and Robert Jolly left for Oregon/California with their four children.

It has been 53 years since the child was abandon at an orphan's home.I don't even know where to begin.

Robert Jolly is deceased and Helen Lorraine Jolly is almost 80 now and very frail.She had years of abuse and is unable to recall much of that part of her life - giving up her children.

Any help would be appreciated.
Thank you