Since a dem is the simplest image from a graphical point of view, you can easily use an online designer to create it (previously, making a demotivator in Photoshop was much more difficult, because this required a special template, as well as minimal skills in working with the program).
There are at least a dozen online designers on the Internet, you just need to choose any one you like. http://demotivators.to/ and http://vdemotivatore.ru/, for example, have a nice interface, but have some limitations in functionality for unregistered users.
We chose the pioneer of this topic - the Demotivation project.
The site map shows all the main sections, including the “Create a demotivator” button – that’s what we need. First, we will be asked to read the very amusingly stated rules, which we can agree with by choosing the option “I’m not an idiot, I understand.” 
Only after this the online constructor itself will open to our eyes.
If the required image is located on your PC, select the required file. If it’s online, we simply indicate a direct link to it in a specially designated column. 
If necessary, you can cut out any necessary fragment from the original image - to do this, check the “Need to cut out part of the image” checkbox. After that, add a title and a demotivator, click “Download!”
You can save your masterpiece by opening it in full size, right-clicking and selecting “Save Image,” or simply save one of the links provided below. There is a direct link to the image, a link to the preview, HTML code, as well as two options for UBB codes (for forums). 
This is what we ended up with.
Our service allows you to easily and quickly make a demotivator from any picture. You don’t have to download additional programs to your computer; with us you can create a demotivator online.
The most important feature of the demotivator is a funny and interesting caption for the picture. Here you can make a caption for the picture in the common form of two slogans. The first slogan is displayed in large font, the second in smaller font.
In order to create a picture demotivator, you need to upload an image file in jpg, png, gif, bmp formats to the site. To do this, click the “Browse” button. Select the required file and click "Upload". Wait for the file to download. The picture will be displayed on the screen. Under the picture you will see a field for the 1st slogan and a field for the 2nd slogan. Fill in the appropriate fields and click “Create demotivator”.
After processing the image, the “Result” field will appear below, where you can see your picture with the original signature in the finished version, which you can save to your computer or immediately publish on social networks.
Reviews
Demotivators are an integral part of the Internet space and social networks. Their main purpose is to lift your spirits. The concept of demotivator is funny photos, pictures about nature, about girls, about love, about everything unusual with original funny comments, meaningful captions written under the image.
This color selection tool will help you choose the desired background and text color for your demotivator.
For example, you can use beautiful light blue 003153 for the background, and white ffffff for the font. In this case, you are more likely to have a form for a motivator rather than a DEmotivator.
For a love picture you can use purple-eggplant color 991199 for the background, and again white font color ffffff.
The main thing when choosing a color is to follow the rule - write in a dark font on a light background, and write in a light font on a dark background. Only in this case will the text be clearly visible.
I think that a proportion of 8 to 10 would be better for the sides of the demotivator.
Let's create a new document (Ctrl+N) 600 by 480 pixels in white and fill it with black. To fill with black, press the keyboard key D, then Alt+Delete. As a result, we will have the following document:
The frame will be double; for the inner frame we will apply the Stroke style with the following parameters:
You won’t be able to apply the stroke a second time, so to create the outer frame you need to dance a little with the tambourine.
First, let's create a new layer located under layer "Photo Area" and rename it "Border":
Now hold down the Ctrl key and click on the thumbnail of the “Photo Area” layer, and the gray square in the working document will be highlighted:
Note. Please note that we still have the "Border" layer active!
Now go to the Selection tab --> Transform the selected area (Select --> Transform Selection) and set the selection value to 103% in width and 104% in height:
Press Enter to apply the transformation.
Now go to the main menu tab Editing --> Stroke (Edit --> Stroke), while the "Rectangular Area" tool should be active in the toolbar:
After clicking on the line, a window will open where we will select the stroke color - white, position - inside and width 3 px:
Click OK, remove selection (Ctrl+D), look at the result:
Now you need to move the photo that you want to see on the demotivator into a working document.
Open the photo in Photoshop and move it into the working document. Learn how to move photos between documents