C++ custom text-to-speech direction

I wanted to try my hands at a from scratch text to speech project for a while now. After gathering .wav files of the different english phonic sounds, and learning how to compile a project with audio PlaySound(TEXT("audio.wav"), NULL, SND_ASYNC); and play it through the .exe, I've ran into the hard part. I can not, for the life of me, figure out a practical way to attach the audio too string or char values so that when the use inputs text, the inputted string is read left to right and plays the audio correlated to the letters it reads.

Where can I go, or what should I look at that could help me with solving this problem or at least aquire the next step?