I need to build my own map renderer
If you have the prerendered images, you can "simply" render them onto a grid of quads. This is done with texturing, i.e. you upload the image to your GPU as a texture and apply texturecoordinates to quads, such that when you render the quads, the textures are applied correctly to their surfaces.

You will however need to learn OpenGL (preferrably with GLSL), Direct3D with HLSL or even Vulkan, all of which will take some time. Depneding on where your goals lie, you may be better of going with a preexisting rendering engine and just learning like Unity or Unreal.

If you do want to learn one of the mentioned Graphics APIs, there are numerous tutorials on the web. For OpenGL I can recommend the youtube tutorials by ThinMatrix, for the other two APIs you'd need to ask someone else. Furthermore, there are splendid books online as well as offline. If you have some money to burn, the basics of rendering are covered in Real-Time Rendering and Mathematics for 3d Game Programming and Computer Graphics. In regards to OpenGL, there are the Online Tutorials of Learn OpenGL, as well as offline books in pdf and epub version.