Hello, i am new to modding,how i can get started to make a mod car?
First, you need to pick a 3D software to build it in (Blender is probably the best choice as it's a free, open source option with professional level capabilities and a massive userbase creating tutorials and addons). Then you need to spend hundreds of hours researching and learning that software.
If you want to create a real vehicle, you'll need to spend dozens or hundreds of hours in researching that vehicle to get a plethora of images, blueprints, detail shots, specifications, dimensions and any other useful reference to recreate it.
You'll need a texture editing app (GIMP is a free software some people use if you don't have access to Photoshop) to create the textures for use on the 3D model. If you don't have or use such a program already, you'll also need to spend dozens of hours learning how to use it for your purposes.
Once you've got a 3D model and textures, you need to export from your modeling app and import it into the KSEditor to set up the final shaders, and then export for use in game.
All along the way you'll need to follow the SDK Pipeline doc to know how to properly set up your 3D model, textures, and other files to get the thing to load in game.
Once you have the model in game, you'll need to spend dozens to hundreds more hours researching how the physics model works, getting all the info for the car you're building, and implementing it all. Then testing and tweaking for dozens or hundreds more hours.
TL;DR it's a LOT of work. If you're up for it, I'd suggest starting with the 3D modeling since you'll be able to watch your own progress, visually, which will hopefully keep you motivated to keep learning.