There are some basic requirements.
For people not using computers;
1) a pen or pencil to draw/write with,
2) a paper to draw upon,
3) a scanner to scan your comic or a camera to take a picture of your comic,
And for people using computers;
1) a basic program like Paint,
2) an editing software (e.g. Adobe Photoshop)
For both of the above categories there is a need for a slight sense of humour and an internet connection.
The first step is creating in your mind a funny scene.
Next, you have to think of appropriate characters for your comic. Keep in mind that the characters you are choosing should coincide with the story of your comic. For example, like in my first comic I have created the scene of a desert, so I made a character with his mouth open (a sign of thirst) and who is dragging himself in search for water. The characters shouldn't be irrelevant for the comic.
Think of a catchy dialogue or statement. I didn't use a dialogue over here, because in comics without scenes, usually there is a use of banners, flyers, or some other text or statement. I'm not saying that there are entirely no dialogues in comics without scenes, dialogues are used (as in my second and third comics), but usually they are discouraged.
Just as mentioned earlier, these comics have no scenes but have only one scene showing the whole picture as one.
Following are some comics having a single scene.
P.S. I'm not really good at drawing cartoons, so what I've done is that I took several pictures from the net or the clip-art collection of MS Office, edited them and combined them using Adobe Photoshop CS 3.
Please vote for me, I will be very grateful.