Need help with Calculation of Correlation Coefficient (and particularly covariance)

Hi guys

In my preparation for a statistics exam (here in Norway), I struggle with calculating the correlation coefficient. It seems like this is supposed to be an easy task, but nevertheless I am not able to calculate the right figures. Here are my example values:

X: 42 39 43 43 38 41 40 42 43 44

Y: 118 68 112 88 140 79 105 113 92 103

And the formula is; Covariance / (\sigma X * \sigma Y) ,

Here are my, probable not correct, calculations:

Xaverage: 41,5

Yaverage: 101,8

\sigma X = 9,67

\sigma Y = 28,01

Covariance = donīt really understand how to calculate it

This is quite a unorganized post, but hope some of you still would care to explain how to calculate the main values needed. Preferrably, examplified by the X- and Y-values in the example.

Pardon me for my English and the structure of this post.