Don't beat yourself up about it, if no-one ever encouraged you or taught you to cook you won't know how to do it!
I strongly recommend these books - Delia's How to Cook and Grub on a Grant.
The second one is aimed at students but is fab for someone who really hasn't cooked before - it tells you how to make spag bol, shepherd's pie, even jacket potatoes!
It's a good idea to get the hang of some basic meals for your daughter, ready prepared stuff has an awful lot of salt and sugar and artificial ingredients. What kitchen equipment do you have - cooker, microwave, pots and pans? And how old is your daughter?
Some ideas (may need modifying if she's under one):
Breakfast - weetabix, toast, scrambled egg, porridge, cheerios, rice krispies, cornflakes, waffles, scotch pancakes, yoghurt, fruit
Lunch - sandwiches with cheese, ham, peanut butter, tuna, salmon, egg mayo, marmite, omelettes, jacket potatoes with cheese, beans, tuna, butter, soup with bread, noodles
Dinner - spag bol, sheps pie, fish pie, jacket potatoes, omelette, fish fingers, mashed potato, fishcakes, sausages, pasta,
Re fruit and veg the best thing I find is to offer it regularly and also as a snack, and don't be afraid to try and offer new things. My girls love bananas, apples, grapes, strawberries, raspberries, blueberries, mango, pineapple, kiwi fruit, satsumas, carrots, broccoli, cauliflower, runner beans, cabbage, sweetcorn, baby corn and mange tout. Funnily enough they're not too keen on peas!