I am a new member who joined to ask some basic questions. I am making a “ear flap hat” and the pattern calls for “casting on” 24 stitches after I knit across one of the ear flaps. I know how to cast on stitches to start a knitting project, but do not know quite how to cast on stitches when I am already in the middle of a project. This is different than an increase and decrease which I do know how to do. Any help or advice would be appreciated. Thank you.