UMPQUA — A teacher turned professional musician will give a crash course Saturday on what she describes as the foundation to contemporary music. Lauren Sheehan says her afternoon performance is intended to entertain, but also to enlighten listeners on American roots music. The concert will be relatively intimate, played to an audience of no more than 100 people inside the barrel room at Henry Estate Winery. This is the Portland singer/songwriter’s second visit to the Umpqua Valley. She appeared at My Coffee and the Wine Experience on Garden Valley Boulevard in 2010. One of 80 female musicians in Washington, D.C.’s …