Choose a photo for the poster. The quality of the image must match the size of the planned poster. For example, from images of size 300 pixels by 200 pixels will not work even poster size A4.
Using the Text tool" in the program "Photoshop", add or stating a funny inscription on the photo. Set the desired type and color of the font. Save the file in jpeg format.
In order to print a large poster size, use a special program, for example, "Easy Poster Printer". This program divides a large image into A4 size pieces that are easy to print at home. After you print the fragments you just have to combine the fragments and hang the poster on the wall.