Rep Power: 0

I was detailing my car and noticed this rust, which is on the bottom of the door. It must have formed this winter because I don't ever remember seeing it before.

https://www.dropbox.com/s/i0ten0s8y2...2016.28.50.jpg

I've never had rust on a car before. Do I need to do anything to fix/seal it? Should I take it to a professional or try and do it myself?

Also I noticed along the floor underneath the door that the paint is chipping, is this a problem? Its almost 13 years old and it lives outside in WI so the weather is hard on it.

https://www.dropbox.com/s/32hweh9vk9...2016.30.01.jpg

https://www.dropbox.com/s/p9igq9nm4v...2016.29.48.jpg

 
Rep Power: 244

You can use a pin to remove the rust, then take a touch up pen and fill it in. Clear coat pen on top of that.

 
Rep Power: 314

Pretty typical wear for a 13 year old car honestly. I'd remove the rust as best as I could and then use a touch up pen as mentioned above. This happens when paint chips go unfilled for a while. How does the inside of the door look. Where the sheet metal folds. This is usually the worst place for rust on doors.

 
Rep Power: 0

You mean like a sewing pin?

 
Rep Power: 244

Exactly! Use that to chip away the rust.

 
Rep Power: 210

When you are dealing with rust you either remove 100% of it or it will be back. How fast it comes back depends on how good a job you do removing the rust and the environment where you live.
Poking it with a pin will at best remove any flaking rust but leave the surface rusted. You will end up sealing the rust under the new paint and it will return. This is the easiest method and if you only need a short term fix it will be OK. The next level would be to sand it to bare metal and then use a "rusty metal" primer before painting. The best solution is to grind or sand blast to bare metal and then treat with a rust conversion coating that will convert the rust to an inactive state. After this you have to fill, prime and paint.