The process - research

What is collage
Definition quoted from Artlex, http://artlex.com/

Collage - a picture or design created by adhering such basically flat elements as newspaper,wallpaper \, printed text and illustrations, photographs,cloth, string etc., to a flat surface, when the result becomes three -dimensional, and might also be called a relief sculpture. Itroduced by the Cubist artists this process was widely used by artists who followed, and is a familiar technique in contemporary art.

•A collage (From the coller, to glue) is a work of formal art, primarily in the visual arts, made from an assemblage of different forms, thus creating a new whole.
en.wikipedia.org/wiki/Collage