install R packages--sorry last letter that I sent I had an error, this one is the right one

Dear All,
 
When I tried to install R packages I found this error:

library(survival)

Loading required package: splines

This is for your information. It is not an error message and is not
asking you to do anything (i.e. it says "loading" not "please load")

install.packages("splines")

--- Please select a CRAN mirror for use in this session ---
Warning message:
package splines is in use and will not be installed 

But I just opened R, and haven't used anything yet, how come did it say "package splines is in use"?

Because it was loaded automatically when you loaded the splines package.
Have a look at the search path with 

search()

You have confused *installing* a package - putting it's files on your
disk - with *loading* it - making it's objects and help pages available
for use in an R session.

Martyn