Okay, I know it's vague, so here is a bit more detailed instruction if you need help. Hope it helps you a lot to!
1) Just mix different shades of yellows, layer them.
2) Blend the colors together, using duh, the blending tool. That's easy.
3) Then use different smaller brushes to make the sun rays streak outward.
4) The dodge tool is what really gives it effect. Use it to just make splotches (it brightens up colors) on your sun, then use it around the edges of the sun, or if you want beams of light shooting from the sun, use the dodge tool. It is easy to learn once you understand how it works. :3
I hope this helps, and this is dedicated to littlebear555.

