chart_2009 <- read.csv('BCHAIN-AVBLS (3).csv')
chart_2009_days = data.frame(date=c(chart_2009[1]))
chart_2009_days["2009 Days of the Week"] <- NA
chart_2009_days[2] <- weekdays(as.Date(chart_2009[1]))

## create a dummy data.frame
df <- data.frame(date = c("2010-01-03", "2010-01-02"))
df
#         date
# 1 2010-01-03
# 2 2010-01-02

## add a new column
df$newColumn <- c("new", "column")
df
#         date newColumn
# 1 2010-01-03       new
# 2 2010-01-02    column

chart_2009$days <- weekdays(as.Date(chart_2009[, 1]))