You will need
  • Adobe Photoshop
Open two or three pictures of your choice that you want to combine into a collage. Determine which photos will be the main background object to work that is already there will be all other objects. Duplicate the layer with the picture.
Now use the move tool and drag on the main background any other photo. Place the layer with the photo under the background layer so that it was between the original background layer and duplicate.
Decide where on the background of the object should be with pictures. Depending on the background image, choose the tool "Lasso", or a mask attached to the layer. Cut out or erase the background layer, those areas which must be located on another photo of the object.
To fit photo size, camera angle and proportions of the objects on background photo, click on "Free Transform" and edit the shape and size of your photos by holding "Shift".

Then make the adjustment of color and brightness of the photo to the background color, this will help you levels) and "Hue\Saturation". You can also open the "Color Balance" and "Curves" to debug the image's appearance.
Follow the same steps with all the pictures you want to place on the background layer. Distribute them in their places, and when all objects are neatly carved and placed on the background, don't forget to adjust the overall appearance of a collage of different objects on it must not vary in brightness and saturation.
Apply to the collage with different settings of the mixing of the layers and choose from them the one that you most like (for example, Soft Light). Finish the job and merge the layers (Merge Visible). The image can be saved and used.