If you are a complete noob then I will highly recommend Tinkercad made by Autodesk. It runs in your browser and is free to use. It’s solid modeling meaning you get cubes, spheres, pyramids etc that you can add and subtract from eachother to get to your final part. It’s a good intuitive start for beginners. If you have any knowledge of programming or is mathematical minded you could try OpenScad that is a text based modeling where you write what you want in terms of cubes spheres etc. I would not recommend FreeCad since it’s very difficult and complex and has a confusing interface.