Hi Han. It's not a "dump question"!
It's a difficult image to fix. The easiest thing would be to find a photo of a similar hill, and replace the fence area. If that's not possible, you could use the "float and move" method...which is what I did here.
1. Basically, select the hill with the lasso and copy it to a new layer. Move the layer behind the background (you will need to need to make the backgroung an editable layer).
2. Now, move this bottom layer several pixels to the right and several pixels down. Return to the top layer, select the fence by whatever method is easiest (I used select by color) and create a mask. The bottom layer will now be revealed wherever you masked out, but since you moved it several pixels over, the fence will be replaced with green grass!
3. You may have to repeat this several times, and then clean the image usiing the clone tool...and add a little noise back into the hill to reduce any fuzziness that developed.
The result is not perfect but hopefully it will give you an idea as to how to approach the problem...although, there may be better ways!