  String geometry theory is a candidate of the non-perturbative formulation of
string theory. In order to determine the string vacuum, we need to clarify how
string backgrounds are described in string geometry theory. In this paper, we
show that the string backgrounds are embedded in configurations of the fields
of a string geometry model. Especially, we show that the configurations satisfy
the equations of motion of the string geometry model if and only if the
embedded string backgrounds satisfy their equations of motion. This means that
classical dynamics of the string backgrounds are described as a part of
classical dynamics in string geometry theory. Furthermore, we define an energy
of the configurations in the string geometry model because they do not depend
on the string geometry time. A string background can be determined by
minimizing the energy.
