You paint OVER it! What you have there is body filler (BADLY done) to cover up the dents and rust on the wing and wheel arch. It SHOULD have been painted over to finish the job and make a weather seal to the repair. I guess your dad is one of those start and never finish a job type of guys.

In the condition the wing is in now you are better off replacing it with another, either new or from a breakers yard (you will need to have EITHER painted so it doesn't matter)

Hi you don't it needs a Body shop to do the work so depending on how big an area that is what it will be. in the cost of getting it done.

That looks like bondo (body filler). If it is, it must be sanded off and repainted.

Do I see rust?

Sand it off or sandblast it off.

How do I get this white stuff of my car. My dad put it on a long time ago like 10 years because there was a scratch but it ended to this so how do I get it off