Making it as a seperate threads will have more responses but I will give you some hints as how you can do that.

how can I insert an image as background of dialog box?
There are couple of ways to be doing this.
1. You need to be doing is Derive a class from the CDialog and use that class for your dialog and in the PAINT message just use the bitblt function to render the image.
2. Add the PAINT message handler to the current dialog and draw the image to the DC of the paint method.
And How I change font of edit box
Using the SetFont method in the InitDialog function of the dialog box where the control is placed.
(but static text must be another font)?
That will remain.