Change labels in a barplot with a ggplot

I know there are already questions about this, but my case is different and I don't know how to do it.

In my tibble there are a column "values" with a value for each observation, "ind" that divides the observations in two groups of equal size, and "average_time" that contatins the average of the group to which the observation belongs.

This is the code I wrote to get the graph:

my_data %>% ggplot(aes(values, x=ind, fill=ind)) + 
geom_bar(stat="summary", fun=mean) + 
 theme_minimal() +
  theme(legend.position="none")

And I get this graph:

Now I want to change the categories at the bottom of each bar from part1 and part2 to "Group 1" and "Group 2", but I can't find a way to do it.

Also, I want to add the average values in the bars. In other words, I want to display the value of each bar in white inside of the bar, something like this:

Can anyone help me with this?