I guess you are using this breakout board? Barometric Pressure Sensor - BMP085 Breakout - SEN-09694 - SparkFun Electronics
It's the same one like i am using, and i am using adafruits library that you can find here..
If you install the lib and open an example that comes with it, you will see the code you can use to read out pressure, altitude, ...
Greetz