what should my activity level be?

I'm trying to get a more accurate picture of how many calories I burn.

I am a student, and walk small amounts per day. I have been wearing a pedometer which calculates how many calories I'm burning, and it says my small amount of walking (about 6000 steps) equates to 250 calories each day. ((At the gym I usually burn 400-500 cals, stay for just over an hour, and I go almost every day)).

So the question is:

1. should I be setting my activity level at sedentary, and just add the excercise that i do at the gym,

2. should I be setting it at sedentary and adding the 250 of walking calories and also adding my calories burned at the gym, 

3. should I be setting it at lightly active and add my gym calories to that,

4. or am I supposed to just have it at lightly active all the time and not add my gym calories?

At the moment, I have been setting it at sedentary and just adding my gym calories (only just bought the pedometer, and wondering if the sedentary level takes general walking into account?). What should I be doing? please help!

I would suggest that you set your activity level to 'very active' because you're at the gym doing vigorous exercise for over an hour a day plus you're active in other ways.  People who are active use more energy when sedentary than people who are genuinely sedentary....  So 'sedentary' + 'activity' can often become an understatement.

If you're under 21 (student?) then the CC calculator is going to understate your energy needs anyway.  This calculator is more appropriate for very young people.   http://www.bcm.edu/cnrc/bodycomp/bmiz2.html   Deduct about 700 from the 'Daily Energy Requirement' number, never going below 1500 (female) or 1800 (male)

You may need to fine-tune your calorie intake as you go along but, generally speaking, it's better to start slightly too high and have to reduce than to start too low and have to increase.

Good luck