I'm a cook, but I've just been through teaching my daughter how to cook, so FWIW I have some experience in this.
First: start on a weekend afternoon when you are not pressed with other commitments. You want to take the time to read and understand the recipe and not get frustrated that you need dinner by X and everything's taking too long and you don't know what you're doing. Set aside some time every weekend at the same time to just practice and work on this stuff (I cook during NFL games, because it gives me an excuse to watch the game instead of doing something more useful).
Second: find a website or cookbook that shows the basics. You need to feel comfortable with the terminology and some basic skills, or it's always going to be intimidating. But don't expect perfection: there is so much froofy perfectionism on TV and in videos and online recipes, but the reality is that for the other 99.9% of us, it doesn't matter if the onion is in perfect 1/4" dice, you know?
Third, lower your expectations. It is 100% entirely fine if "dinner" means grilled cheese sandwiches and a can of soup, or a box of mac and cheese, or whatever. I have been cooking for @40 years, and I still have hot dogs and pierogis as a fallback every week or two. The important thing is to get a variety of healthy foods over the long-term, so don't stress if every meal isn't perfect. And also don't stress about getting the lowest grocery bill as soon as possible. It's ok to use a bag of prewashed lettuce or steamable frozen vegetables if it helps get some nutrition on the plate and avoids takeout, you know?
Fourth, take it slow. Start with one or two simple things you think you can make. Take full advantage of premade options at this point, e.g., a box of pasta and a jar of sauce. When you have time, think about how you might be able to tweak those things to suit your family -- so maybe you want to brown up some hamburger to put in the sauce. Once you have a couple of meals that you feel comfortable with, you will have a little more confidence, and can move on to trying new ones, and moving away from some of the prepackaged stuff.
Finally, consider paying for a service that will help you. I had a subscription to Cooksmarts for a year or two -- not because I needed the help with the cooking, but because I was tired of menu-planning, and they made it SO easy. They make things very, very simple for you: they give you 5 recipes for the week, which are designed around re-using the various ingredients (e.g., if you have some kind of chicken breast Monday, you might have a salad topped with leftover chicken Thursday). They break the recipes down into phases and lay out what you can do in advance, and include videos of various techniques if you're not sure what they are -- and the recipes are pretty simple and easy to make (designed for normal people with jobs and kids, not people who enjoy spending hours in the kitchen). And my favorite part: they give you a grocery list based on the meals you have selected and the quantities you will need, so you can go right to the grocery store and get the right amount of food, so you don't end up throwing out half your veg because they went bad before you used them.
The big thing is just to get over the intimidation and build new habits focused around eating at home, so whatever you need to do to get over that hump is ok by me. I personally liked cooksmarts because they took the thinking and planning and everything out of it, so I didn't have that sinking feeling of "gah, now I have to sit down and figure out what to make that everyone will eat and do the grocery list and all that." But you need to find what works for you.
Oh: and as an example of how simple "cooking" can be, here's a recipe that actually makes me feel guilty, because it tastes so damn good and involves so little actual effort: White chili.
Take some boneless, skinless chicken breasts or ground turkey or whatever you want and dump them in a slow cooker -- maybe 1-2 lbs, quantity doesn't really matter. Take two cans of any kind of white beans, rinse them in a colander, and dump them in. Take a jar of salsa, dump it in. Add about 2 cups of shredded mild cheese. Add a few teaspoons of some spices -- I like a few poultry-friendly spices (poultry spice or sage and thyme) and a few classic chili spices (chili powder, or cumin and some sort of smoked paprika or chipotle) -- but don't worry about getting quantities perfect, because you can always add more at the end if it is too bland. Put the lid on and cook for @4 hours, or as long as you want -- add a little water or chicken stock if it seems to be getting too dry. Shred chicken, stir everything up, taste and add more spices or salt/pepper if you want, serve with whatever chili toppings you like.
Yes, that is "cooking." And it is freaking delicious -- and makes enough for multiple dinners for the 4 of us and several more lunches for me.
