unity weirdness problems

So i am pretty much a noob when it comes to unity, however, i need to make a quick demo of something for school, which is one “environment”. I tried putting in in a height map, to achieve some variety, but as soon as i input any height, be it my own or one from google, weird things happen. Did I forget to import something or added the wrong values? or is it just because it is the free version?
extra image for clearness

Did you import the heightmap from another program? I haven’t done it in a while, but I think it has to be a certain .RAW file with the correct settings. I’m not sure if you can edit them afterwards.

See the bottom of this page: http://docs.unity3d.com/Documentation/Components/terrain-Height.html

And look here: Issue with importing raw heightmaps (made in photoshop) - Questions & Answers - Unity Discussions

Apparently it was just the fact that i saved a grayscale file in rgb modus. whoops.
Thank you for the help and sorry for bothering!