Here is an easy command in R in order to test 
linear hypotheses in the Gauss-Markov setup. 
Of course you can do the programming yourself, 
but this command makes life somewhat easier. 
You will first need to download the "car" package 
from CRAN. This is easily done. Connect to the 
internet, open R, and use the command:

install.packages("car");

The command for testing hypotheses is: 

linear.hypothesis();

You will need to load the library before proceeding 
with that command, through: 

library(car);

When using linear.hypothesis(), you will need to specify 
a hypothesis matrix. For details, check the 
help(linear.hypothesis) command. It spells things out very clearly.

Note that the "car" package has lots of other goodies that 
you might want to explore.