What should I do about this rust? Pics included.

[KC10Chief]

I have two rust spots on my 91 Explorer. One is on the passenger side, below the back door and just in front of the rear tire. The other is next to the rear window wiper. Keep in mind, I paid $800 for this truck. I don't want to spend two weeks making it look brand new. I just want to get it stopped. If I can fill it with something, that would be great too. I'm not real concerned about the appearance. Bondo? I've never done it before.

 

[Glen4X4]

if that's all the more rust you have then your doing good. don't know what tools or skills you have access to but I would cut those sections out and weld in some metal and slowly form the shape of the rocker to curve around since it doesn't appear to be a big area. But I would take a good look behind the running boards.