Light Texture Tutorial?

I've browsed through the memories but I can't seem to find what I'm looking for. Is there any tutorial on how to Make light textures? I've been dying to find out! And I never saw any post here on how to make them..So if you could point me to a tutorial maybe? An example of a light texture is in my icon, the flare dots..

Much Love
xoxo Yasmeen

Thank you for any help at all!