df <- data.frame(x =1:44,
                 For =as.numeric(forecast),
                 L1 =forecast.CI3,
                 L2 =forecast.CI4,
                 U2 =forecast.CI2,
                 U1 =forecast.CI1,
                 TR =as.numeric(test))

ggplot(df,aes(x))+
  geom_line(aes(y=For,color="black"))+
  geom_ribbon(aes(ymin=L2, ymax=U2),fill="grey90")+
  geom_ribbon(aes(ymin=L1, ymax=U1), fill="grey80")+
  geom_line(aes(y=TR,color="red"))+
  xlab("Forecast Steps (Day)") +
  ylab("Daily Demand (MW)") +
  theme_bw(base_size=13)+
  theme(axis.title.y=element_text(margin=margin(0,15,0,0)),
        axis.title.x=element_text(margin=margin(15,0,0,0)))