Hello balboadale and Patapuss, and welcome to the forum!
There are a huge number of possibilities when adding LED lighting to a home. What works for you will depend a lot on your application.
First decision: battery or line power.
I have some battery powered LED lights around the house. In the master bedroom closet, there's a puck on the inside of the door which you press to turn on or off. That's so you can enter the closet, close the door, and turn on the light without bothering the snoring spouse. I have the skills to add a switch inside the closet for the line powered light, but this was a lot easier. Tradeoff is that the light isn't as good.
Battery powered lights are super easy to add, but they don't generally provide as good light as line powered units, and of course eat batteries if you use them much.
All LED lights (including line powered ones) require some sort of driver. In battery powered units this is built in.
For line powered LED lights, sometimes the driver is incorporated into the fixture, and all you have to do is provide line voltage to each fixture. Wait a minute, that requires knowledge of how to safely wire line voltage in your house.
Let's say you don't have that knowledge. You want LOW VOLTAGE lights. These can be safely wired by anyone with basic ability to follow directions. You'll need to plug a driver (maybe called a transformer) into an existing outlet, but once that's done everything else is very safe, and fairly easy. If you can assemble an IKEA bookcase, you can install low voltage lighting.
If you don't have an outlet where you need it, you may have to hire an electrician to provide one. After that, you should be able to install the lights yourself.
I hope that helps as an introduction. Please ask any follow-up questions, as there's a lot of knowledge here in the forum, and I hope we can help you on your journey.
