The word "collage" mean to paste; it's a work of art made by pasting or gluing objects onto a background. It's a good idea to do the pasting on a heavy piece of cardboard, so your art work won't buckle and bend when it dries. The fun part is that you can glue on so many surprisingly different things.
It's fun to experiment with combinations of materials in your art. Try making a drawing of something real or just a design, using colored chalk on dark paper. Press hard as you draw with your chalk, and your lines will really stand out against the dark colored background.
Next you can tear or cut pieces of paper to glue into the spaces between your lines, to "color in" the spaces, trying not to cover up the bold chalk lines you made. Here are some things you can use to glue in the spaces: torn or cut colored or patterned papers, yarn or string, colored tape, cardboard, buttons, old calendar pages, newspaper, wrapping paper, ribbons, magazine pictures, pieces of hand-written letters or envelopes, old movie tickets... Can you think of any other things to glue on?
Try overlapping your glued-on pieces, linking one shape to another, and allowing some colors to peek out. Pablo Picasso and Georges Braque and Kurt Schwitters were artists who made beautiful collages.
It's a good idea to keep a box of collage materials handy at home, and you can keep adding recycled papers and objects to it, as they become available. Artists have always been great "recyclers."