NZFF

Can any one point me in the right direction or help me with modifying terrain in FSX. I have used TmfViewer to identify the file of the area I want to change. Also I have installed SBuilder X(Is this the tool I need to use). But I can not find out how to use these tools together to add land where there is water. I have read a few tutorials but they don't seem to explain how to just add extra land mesh onto a water area.
Any help would be appreciated.

Dunno the answer, but have you tried FSDeveloper.com? They've been a great help with my own scenery project (trying to figure out sloping flattens at the moment...)

So you want to add a 'hill' to a new area of land? or just want to add the land without the 'hill'? (Sorry, some people use the word 'mesh' to describe everything from roads to landclass......Mesh, at least from my background, refers to terrain elevation data)

Im guessing the easiest way to scratch build Elevation mesh data for a new piece of land (such as an Island) is to create a grey scale TIFF- Every pixel value relates to a elevation...but it would be a lot of trial and error.

Yes, there is a difference between correcting an area with a poorly formed coastline, and creating a fictional landmass. If you are correcting an area, the elevation may already be there, it may just be flattened by water polygons.
Normally you wouldn't alter default files in FSX, you'd exclude the existing polys and lay down your new polys.
Take a look at FSX KML over at FSDeveloper.

Thanks for that, I am wanting to modify a coastline to have a land area further out into the existing water area and remove a river. The height elevation wont mater.
This is for a fictitious project I am working on.