The real question is whether you think you did a good job or not. Your renders need alot of work. All thos jagged edges and whatnot. The pictures used in the wallpaper look distorted, possibly done while you were resizing them. Keep in mind that these are suggestions for the future, and in order for you to improve you gotta take some constructive criticism.

In any case, if the only program you have right now is MS Paint, I suggest your grab some sort of version for Adobe Photoshop and learn how to use it well.