Don’t use sunbum (I don’t know it, but I’m assuming it’s a spray in sun lightener?). It causes a lot more damage than is worth it for the affect you get. If you’re not careful you’ll just get patchy orange.
The best way to get this look is over time in my opinion. Well placed highlights or balayage to start with will give you an all over look not unlike this, but it’s the times after that will bring you closer to the natural sunkissed blonde look. Each time the ends get lightened a little more some being processed a second time and some being processed the first time, it gives you a more natural effect. It gives that gentle ombré to pale golden blonde at the bottom. They would either use bleach or dye to do this.
It’s hard to say it’ll need toning as it depends if they use dye or bleach and how much red and yellow your hair has in it. I don’t know how brown your hair is, or if it’s a warm or cool brown, so I can’t guess
