I can not really give you a step by step set of instructions on how to remove something from a picture. There's usually more than one method. I suspect there are tutorials around either on the web or even within Photoshop's own tutorial section.

Personally, I usually use the Clone Stamp Tool to paint the surroundings over the top of what it is I wish to remove, as long as it's only a relatively small area without too much varied detail surrounding it which makes the process much more complicated. For example, you can clone from a point just above or below one of the power lines and clone (press your cursor) over the power line. This can take a lot of practice to get right. In your case it might be safer to create a new layer. Have the original layer selected and set the clone point (by holding down Option key or presumably Alt key for Windows and clicking where you wish to copy from). Then go to the new layer and start cloning (by clicking your cursor point where you wish to copy to.) Problem with using a different layer is forgetting the exact point you cloned from. Perhaps zoom the image as large as you can to reduce chances of this error. Another problem is if you wish to select a new clone point you need to remember to go back to the original layer.

Another very similar tool is the Healing Brush Tool.

When I get time I might be able to do a sample for you.