Hello, I'm new up there ! I'm not very good in Rstudio so please be patient lol (and i'm french so non native english speaker)

I'm in master's degree internship and I have collected data of bacteria concentration (cell/ml) above time (in days of experiment). So My supervisor wants me to plot the abundance above time and to add exponential trendline (with equation of the trendline and Rsquare). As simple as it is on Excel, i would like to do it on R, but I NEVER SUCCEDED and I went on so many website. I don't understand why this seems so complicated. I really need help because my internship end soon, so please if someone succeed to help me, I would appreciate.

Someone on stack overflow told me to just copy the curve given by excel, but I'm sure there is a way to calculate it with Rstudio.

Also on Excel, you can choose to trace the tendance curve on just some point of the data but still plot all the point (idk if this is clear but), for example let's imagine I know from what I see when I plot my data, that there is an exponential growth from the day 1 to day 6, and after it "calm down" and decrease. So I just want the exponential trendline to be calculated from the day 1 to 6. is it possible on R ??

Please, I beg someone to help me ..

here are an example of my data

C2A <- data.frame(cell = c(7.07*10000,
5.28*10000,

5.42

*10000,*

5.5810000,

5.58

1.26

*100000,*

1.121000000,

1.12

1.55

*1000000,*

2.501000000,

2.50

3.34*1000000),

day = c(0,3,4,5,7,11,12,13,14))