Chrmak isn't a regular program. It has no GUI. You can use it a couple of ways though.
1. Command Prompt. But I don't think you'll want to get into that.
2. Drag and Drop .mak files onto the program icon.
3. Open the .mak files after setting the default program to open them as Chrmak.
But really, it'd be easier (for most people, I use Chrmak) to use VOpenChr instead of Chrmak. Get it
here.