如何使用windows.h将字符串输出到c中的文本框中?

I'm making a program in c that uses a gui to help accomplish a task. The program is supposed to increment each character value inputted by the amount in the key. I am having problems with this however, I can't figure out how to debug it properly, because I can't really output text to the screen at certain points of the code. My problem though seems to be that I'm not quite sure how to accomplish outputting text to a text box with windows.h. Can anyone figure it out?I'm making a program in c that uses a gui to he