Help with KillMarks

Hello to all, i came here to ask if anyone can help me in this killmarks, they are col for me but they have white background :/ can anyone tell me how to delet that background please? they are just letters :O like:

1 first kill
2 double kill
3 multi kill

I give thanks if you help me

I use paint.net and photoshop i use paint for little things and photshop for signs, killmarks etc...
But thanks i will try.
BTW 1 thanks for you