How can I fix my airport from going in the land like so?(AFX, fsx)

If you want to do it without a lot of learning, make an apron ever so smaller than the runway and slide it under the runway. It will flatten the terrain for the runway to sit on.If you want to approach it in a more appropriate manner, then you need to use a tool like SBuilderX or FSX KML. These will allow you to remove the old Airport Boundary and make a new one at your runway's elevation. If you look to use SBuilderX, I recommend grabbing the scenery design tutorials done by Luis Feliz-Tirado, available here in the file library.

Thanks, I did it the easy way but im going to download Sbuider and see what it can do...