The Concord Senior Center is hosting a workshop for people who want to learn about the role of social security, Medicare, pensions and plans such as 401Ks and IRAs in retirement. The workshop will take place for an hour a week over three weeks on Tuesdays, Jan. 10, 17 and 24, from 7 p.m. to 8 p.m. The sessions will be held at the Senior Center, 2727 Parkside Circle.