Take a deep breath, that's number one.
The idea behind the calorie deficit is to eat fewer calories than you burn in a day. If you have something like an iphone, I'd recommend the LoseIt app (it's free). I'm sure there are similar free programs on the web. The idea is that you input your height, weight, age, gender, goal weight, and how quickly you want to lose, and it will tell you how many calories you should consume in a day.
My recommendation to you would be to try a plan for 1-2 weeks and see if it's something you can stick with. If not, try something else.
Some general good ways to start:
* Cut out the refined sugars and carbs (no white breads, white rice, soda, etc.)
* Eat lots of lean protein
* Eat your veggies
* Drink lots of water
* Start doing a little bit of physical activity, building it up gradually -- even if it's just going for a walk.
* Keep a log of what you eat, how much, and the calories. There are lots of sites on the web that will give you the calories for basic things like meats and veggies, and all packages have nutrition info on the side/back. Pay attention to portion sizes. At first, try to eat around maybe 1500-1600 calories a day, then bring it down.
* Most of all, don't try to do everything all at once. That's a great way to get discouraged.
Keep posting here, and check out what others have said. Not every plan works for everybody, but people here do find what they need (just check out the goals section for some inspiration!). We're all here to help and support you.
Good luck!