File is set to grayscale, how do I add a image in the file without it becoming gray?

[Walpurgisnacht]

   
Disclaimer:I have zero knowledge on GIMP and I'm using it only because it's the free alternative to Photoshop. 
So my problem is: I need to add an image to another file that is in Grayscale set in default. When I try to add an image, that Image to becomes gray too. How do I restore that image colors or prevent it from becoming gray?

[Ofnuts]

Make the first image RGB (Image > Mode > RGB) once it is a loaded in Gimp, and before you add the color image to it; Another solution is to add the grayscale image to the color image.