To power LEDs from the fuse box in your car, the first thing you need to do is find the right fuse. Then, you need to ask yourself when do you want the lights to come on? With the headlights or when you turn on the car. Obviously, this largely depends on the kind of LEDs you’re looking to install.
If you want them to come on with the headlights, you need to find the fuse that controls the inside lights of your car. However, if you want the lights to come on when the car is on, choose the fuse that controls your radio or even your ignition – this implies that when these things are turned on, the lights will be on as well.
Alternatively, you can run new wiring for your extra lights to avoid complications in your car’s performance.
I was just at a car specialist place and they said I should tap into the ignition cord and use a product like the ATC Fuse holder (https://www.oznium.com/install-bay/atc-fuse-holder) but i don’t know what else I’m supposed to attach. And also which wire is which on the LEDs? I have 2 green flex strips (https://www.oznium.com/flexible-led-strips/led-flex-strips)
You could do it that way if you wanted to but I would recommend another way. If you tap into your ignition wire then it’s already fused. If you buy the fuse holder I would recommend running a new wire from the battery into the car. It’s not hard to do and will allow you to expand your glow later (everyone does eventually). I’m not 100% sure about which wire is positive but I believe it’s the silver wire. Read the FAQ on the flex strip product page and you will find it there.
If you’re going to run a wire from the battery look through the forums for one of the Oz labs videos (maybe someone can post it here if they’re feeling ambitious). Also, there’s a thread that helps to determine what fuse size you will need.