[Request]-Rust wall chipping texture in gimp 2.4

[lilgrudgeboy]

Hi all

(FEEL FREE TO SKIP A HEAD)
i am learning how to hand paint textures in gimp(no moneys to buy photoshop) i dont have a Wacom or anything so im using my good old fashion mouse

i have been looking and looking for gimp tutorials..all i find in photoshop..i have followed some PS tuts but i gave up because it got confusing...i have made a few textures here..they are the 1st i have ever made..
my main goal is to be able to texture any image i see..not 100% spot on

but here is what i need is a good tut on how to make rust then wall like this or like this

so please if there is any one out there that can help i would thank you a million times