Steps

At the first step, i started by creating a square using the rectangle tool.

Secondly, i use Pen Tool to make an almost triangle look alike. This is for the land/beach.

I add few anchor with the Add anchor point tool to make a few curves.

After satisfied with the shape, i adjust the colour of the beach and the sea. For the sea, i used gradient.

I also applied the same thing to the beach for its 'fill'.

Next, i added a green land and made it using the pen tool.

Then i used the rectangle tool again to make a building. I also changed the gradient for the sea as i thought that the previous gradient didn't look good.

I copied the first building i made and paste it for a few times. Then i placed it near each other and i had also adjust the size so it would look more like a city.

For the window, i made a very small square using the rectangle tool and copied it then paste it for many times. After that, i placed it around on each building i've made.

Next, I copied the beach layer and paste it for about 3 times. Then i moved the new copy of layer a bit lower from the original layer.

For this step, i removed the stroke and reduce the opacity for the copied layer to make it looks like the beach is fading into the sea.

Next, i made a big rectangle using the rectangle tool and surround the canvas outline.This is to crop the image.

As seen in the screenshot above, i did that to crop the image so that things outside the outline won't be visible when i export it.

The final outcome.

Reference for the 2nd assignment

Here are few reference pictures for my 2nd assignment that i've found on the net regarding the 'Sea Level Rise' effect.

Coastal population centers at low elevations like New Orleans, Key West, and other spots around the world, are vulnerable to sea level rise. Florida's Key West floods routinely in springtime when tides pulled higher by the new or full moon reach 1.7 feet above mean sea level. (Photo courtesy National Weather Service Forecast Office, Key West; NOAA Photo Library.)

Source : http://www.ucar.edu/news/releases/2005/change.shtml

From Vanity Fair, a photo of what Manhattan might look like if sea levels continue to rise. Photo illustration by John Blackford; original photograph by Cameron Davidson. Related article: “While Washington Slept,” by Mark Hertsgaard.

Source : http://www.notesofintelligence.com/2007/01/25/manhattan-after-sea-levels-rise/