Place all the materials you will be working with on a bench or table. Draw out the type of float you wish to build and create the design team to assist you. For this example, a box float will be built. You might want to research the Internet for design ideas.
Take the shoebox and remove the lid. Cut a hole at the bottom of the box that is big enough push a doll through the bottom. Use the colored crepe paper to cover the box so you cannot see how it looked originally. Place the various colored tissues on the box and add the pictures and balloons. Be sure to cover the entire surface.
Using the rest of the colored crepe paper, cover the lid of the box and use some use to attach it to the base of the box. Add the decorative items to the top of the box like you did to the bottom. Be sure to cover the inside top of the box as well.
Create a "skirt" that will reach around the edges of the box and around on the top. This will give your float the same look at the large ones. You can make the skirt from fringe ribbons or party streamers. You can attach to the edges with glue or stapler.