Draw a straight, horizontal line across the middle of your piece of paper. This will be the horizon line, the line where the sea meets the sky. You can use a ruler to help you draw a straight line. Below the horizon line, but not quite at the bottom of your paper, draw a wavy line across your whole page. This will mark the tide-line, where the water reaches the sand. Make the curves of the line different sizes to make the waterline look more realistic. Your scene will have the beach in the bottom part of your page, then the water, and then the sky. Make it clear that the ocean is water by adding little squiggles to look like waves. Don’t worry too much about making it look perfect. You are just at the pencil stage, and can fix it up later with colors. To draw a cloud, sketch short, connected curved lines. You can make the clouds as big or small as you want, and can also add swirls in the middle of the cloud for a more realistic effect. If you want your beach scene to be perfectly sunny, with no clouds, then feel free to skip them! If you want your beach scene to take place at sunrise or sunset, then draw the sun as half a circle, sticking out of your horizon line, in the middle of the page. If you want your beach scene to take place in the middle of the day, then draw the sun as a full circle floating in the sky. If your scene is at night, add a moon by either drawing a circle or a crescent.  Don’t worry if the circle isn’t perfect! Most of the time people don’t look directly at the sun, so they don’t really see a perfect circle. If you want, you can give your sun a friendly smiley face.

TL;DR in Indonesian:
Gambarlah garis cakrawala dengan pensil. Tambahkan garis bergelombang untuk tepian air. Buat lengkung-lengkung kecil di air untuk membentuk gelombang. Gambarlah awan di langit. Gambarlah matahari atau bulan.