These commands should be enough to get you through the necessary activities:

read.csv : Use this to read/import a comma seperated value data file (the most common type).
read.csv("data.csv") : will read a data file called data.cvs which must be located in your working directory.
var = read.csv("data.csv") : will create an object called var in your working directory which contains the data in data.csv, in the same row and column structure.
var = read.table("data.dat") : will create an object called var in your working directory which contains the data in data.dat. Use this if the data table to be read in is not seperated by commas.
var1 = var[[1]] : will create an object called var1 which contains only the first column of var. Please not the double square brackets, this is very important.
plot(var1,var2) : will plot the var1 on the x axis and var2 on the y axis. There must the same number of values in var1 and var2 (a y for every x).
hist(var1,breaks=10) : will plot a histogram of the values in var1 broken up into 10 bins.
var2=var1[var1[1]>10 : will create an object var2 which contains the values of var1 where the first column of var1 is greater than 10.