Why does readymade food always have so much flavor to it?
Readymade foods use flavour enhancers, artificial flavours and other additives that improve the mouthfeel and appearance of their product. Most ingredients lose much of their appeal during industrial processing so this kind of trickery is necessary.

Undoubtedly you can make food that tastes much better than readymade. There really is no substitute for freshly made food made from in-season fruit and vegetables. It's difficult to give general advice on how to do this. There is a great deal to learn before you can cook flavourful food consistently. I have been serious about cooking for about four years now and my cooking, if I'm to be honest, is still a bit hit-and-miss.

I suggest you start with some good, dependable recipes. The recipes on the America's Test Kitchen site are developed with simplicity in mind and don't compromise too much on flavour. I started cooking with a recipe book from Heston Blumenthal which was technically challenging but also a great way to learn a lot about cooking in a short space of time. There are more cookbook ideas in this (closed) question.

Try a recipe. If it doesn't turn out as you had hoped, do some research and try again. If you are still having trouble you can always come back here for more specific advice.