Strcut Allocation problem with pointers

Hi everybody, i am new to CUDA and i am working on fire forest diffusion simulation. I need to define a struct as follows

struct image
int width;   //to hold the number of rows of the grid
int height;  //to hold the number of columns of the grid
int *gridCellState;
image *img,*img_d;

I allocated memory for both variables as follows

img = (image *)malloc(size_image);

I dont know whether this allocation is correct or no and the next problem is how to initialize img->gridCellState and how to move it to the device and then back again from device to host.

I would like to thanks you for your help previously.