Born in Cumberland, Maryland, Gen. Deener attended Western Maryland College (now McDaniel College), earning a Bachelor of Science degree in studio arts in 1975. She then moved on to receive a Masters of Science degree from Frostburg State College in Business Management in 1978. After graduating from Western Maryland College, Gen. Deener joined the United States Army Reserve and worked as a clerk in a supply company, beginning her career with the United States Military when few women worked in this field. She received a commission through the Maryland Army National Guard Officer Candidate School as a second lieutenant in 1978, starting her service with the Maryland Army National Guard. 

Because of the restraints on women, Gen. Deener worked as a medical corps officer, one of the few military careers available to women at this time. She continued to push into new fields, however, and became a training officer at the Maryland Military Academy, eventually becoming senior training officer at the Officer Candidate School located at the Academy. From here, Gen. Deener began working full-time for the Maryland Army National Guard as a personnel and administration officer, ultimately working as the Director of Information System Management, the Director of Military Personnel, and the Director of Human Resources. Holding these positions made Gen. Deener the only person in the Maryland Army National Guard�s history to hold three directorate level positions.

Gen. Deener also earned the distinction of being only the second woman to attain this rank in the Maryland Army National Guard full-time workforce. Her career continued to advance and in 2005, she was appointed to the position of Chief of Staff of the Maryland National Guard, managing over 5300 members of the Maryland National Guard and becoming the first woman to hold this position.