Fran is spot on with that advice. Before I knew much about what I was doing, my weight loss journey began with simple numbers and common sense. Calories consumed versus calories burned. It's not totally that simple, but it's a great place to get started.
Portion control, sensible nutritive foods and just a little increase in activity pay off. I lost 70 of my 100 lbs without really knowing what I was doing simply by cutting my (admittedly sizeable) portions in half and learning to stretch my meals over a couple days by eating them as leftovers. I consumed ridiculous amounts of water and started walking a couple miles a few days a week. The common sense things like reducing sugar (this is where almost ALL of your added body fat comes from), increasing fiber intake, and eating more plant-based meals really started to pay off after I started focusing on my nutrition a bit more.
The body naturally wants to reach what's termed homeostasis. There is an optimal level at which it is designed to run. The problem is we fail to feed it what it DOES need and we excel in feeding it what it DOES NOT need in order to run there. What I've found is that nutrition is without a doubt the biggest place we miss out on helping our body run right.
As an addendum to what Fran said about fibromyalgia and metabolism, there is very strong evidence that supports that statement. Many things point to hypothyroidism (and low-grade whole-body inflammation) as a very likely culprit in many fibro symptoms.
Toxins like fluoride in tap water, bromine in many bread products and even your very own estrogen production blunts the message that your thyroid sends out to every cell in your body. These chemicals occupy the hormone receptors on each cell giving the thyroid hormones no place to be received. Also, since women produce so much more estrogen than men, women suffer from thyroid problems at a much higher rate. Watching for these things can help as well as taking steps to detoxify your body.
Lastly, if you're only goal is to lose a quick ten pounds and it is truly important to you, there is no better place to start than with what you are drinking.
Drink ZERO glasses of soda of any kind and replace it with H2O. Not tap water and not the kind in the cheap, crinkly plastic bottles full of BPA that leaches into the water. You will learn to love water for all the good it does for you
And you will absolutely lose weight by taking this simple step. If all other things are held constant, your body literally has no choice but to do so.