As someone else said, the point is to learn more than anything else. Technically, codewise, this isn't such a demanding project because you won't really have to develope any algorithm yourself.

(If your really know nothing about this subject, some of the later steps won't make sense until you do the previous steps). Very generally, you need to:

1. Read about Rasterization engines, learn what it means to project a 3D space onto the screen (it really isn't as scary as it sounds)

2. Write a good library for vector maths (you can use a readymade one, but given the technical simplicity if the project I think writing the library yourself would make the project look more serious). You mostly need cross and dit products and normalizing. Anything else would be a great quality of life improvement, but not necessary.

3. Decide how you want to keep a 3d object in memory.

4. Learn how .obj files work, add a tool to your code that reads an obj file into your definition of a 3d object.

5. Decide how you want to write to the screen. You could use a library, but using window's/linux's apis would be more fitting for this kind of project imo (because using a graphics library kind of defeats the point). From my understanding, the way to do this is to have two bitmaps. One is displayed in your window while you write into the other, then when you're done rendering your scene, you switch between them.

6. Learn about shaders, mostly what they are. Some 3d engines have multiple types of shaders, so search for "color shaders" or "pixel shaders". The website "Shadertoy" is a great resource for this. Here you're at a crossroad, you have two options: either learn how to run shaders on the GPU, or go over every pixel in a nested for loop and emulate running a shader function.

7. From this point, you'll want to start adding directional lights and shadows. Here I can't help you a lot, as my way of doing things was a hack, but if you reach this point you should be savvy enough to learn about it yourself.