If you want to place a character on screen, the basic spots are:
@CHARACTER stands screen right
@CHARACTER stands screen center
@CHARACTER stands screen left
@CHARACTER stands upscreen left
@CHARACTER stands upscreen right
@CHARACTER stands back far left
@CHARACTER stands back left
@CHARACTER stands back right
@CHARACTER stands back far right
@CHARACTER stands offscreen right
@CHARACTER stands offscreen left
Something a little more advanced (not hard at all) would be spot placing. Here is a thread that covers that.
Also, if you search Joseph Evans on youtube he has many tutorials that teach you the basics of directing and more advanced things!