Alright, when I go into some multiplayer server, I see some people have custom skins like "RedBull" markings. Do I have to make my own to use one or can I take a skin and use it on a car of mine? If so, how do I access them?

You can either:
- get a skin in .jpg format from others (will be named like "XRG_niceskin.jpg"), you copy it to LFS/data/skins, and you can select that skin in Garage (New colours - Choose your skin file)
- create one yourself, and copy to the same folder mentioned.

You can find a great Skin tutorial on the LFSManual: https://en.lfsmanual.net/wiki/Skin_Tutorial, which should answer most of your questions (about details on skin creation; whether others will see your skin etc.). Should you have any questions not answered there, feel free to ask here

For multiplayer: You need upload at your lfs account top right, you press your usernamne, car skins, upload.