I’m sure with google, you’ll find a lot of information and code.
Once you have the 3D data (x,y,z coordinates), you might want to transform them using 3x3 transformation matrices. So you’ll need to implement a matrix multiplication function. (search transformation matrix, rotation matrix, etc)
Showing a 3d model on a 2d screeen is essentially:
Defining a viewport (== defining center, scale, perspective, etc).
Drawing stuff at the x,y coördinates, and use the z value for ordering. You can keep all coördinates ordered by its z value in an array. And drawing happens from the back to the front.
You also need the z value to apply perspective view. The closer an object is to the viewer, the wider x/y coördinates are apart from the center. So you simply multiply x and y coördinates with a fraction of the z value.