Adding legend to ggplot for clearity

Question

so I need to add a legend to this. I have the feeling I am doing something wrong with the aes() function, but I could be wrong. Here is my code:

library(readxl)
library(ggplot2)
library(ggpmisc)

Mydata <- read_excel('../...') #Data file
df <- subset(data.frame(x1 = Mydata$rc, y1 = Mydata$`O2 (mol/m^3)`), y1 > 0.051 & x1 > 0)         #Points that do count
df2 <- subset(data.frame(x2 = Mydata$rc, y2 = Mydata$`O2 (mol/m^3)`), y2 < 0.051 & y2 > 0)        #Point not taken into account
cols = c('Included in regression' = 'blue', 'Excluded from regression' = 'blue')
fills = c('Included in regression' = 'blue', 'Excluded from regression' = 'white')

ggplot()+
  geom_point(data = df, aes(x1,y1), color = 'blue')+
  geom_point(data = df2, aes(x2,y2), color = 'blue', pch = 1)+
  geom_path(data = df, aes(x1,y1), color = 'blue')+
  geom_smooth(data = df, aes(x1,y1), formula = y~x, method = 'lm', se = FALSE, color = 'red')+
  stat_poly_eq(data = df, formula = y~x, rr.digits = 3, coef.digits = 5,
               aes(x1,y1, label = paste("atop(", after_stat(eq.label), ",", after_stat(rr.label), ")", sep = "")), 
               parse = TRUE, label.x = 'right')+
  xlab(expression('dC'[O2]*'/dt (mol m'^-3*' s'^-1*')'))+
  ylab(expression('C'['O2']*' (mol m'^-3*')'))+
  coord_cartesian(xlim = c(0, 0.00205),ylim = c(0,0.27),expand = c(0,0))+
  theme_bw() + 
  theme(panel.border = element_blank(),
        panel.grid.minor = element_blank(), axis.line = element_line(colour = "black"))

Answer 1

Put your color = '<color>' statements inside aes(). For example,

geom_point(data = df, aes(x1,y1,color = 'blue')) 

It's likely your going to want to manage the labels in the legend. In this case, you can use

geom_point(data = df, aes(x1,y1,color = 'mylabel')) + 
scale_color_manual(values=c('mylabel'='blue')) 

and the legend label will be "mylabel".