Of course, you will see another files in lib folder that you extract. There are files of dynamic library (*.dll). All of these files must put in project folder which already existed in the folder Codeblocks. Then, open Codeblocks and click Settings -> Compiler and debugger menu. So that you will see Global compiler settings application window.
In the Add Library window, click Browse, we remind you again, SDL_image.lib make sure you've put in the lib folder of the folder CodeBlocks. After getting SDL_image.lib then click ok. SDL_image.lib then there will be on the list of linker settings. After that click ok on global compiler settings. While SDL_image.dll files you put on the project folder. To ensure what you done is working, see the video from us, you can put another file of png (portable network graphics). In this movie we using windows 7, but basicly it same.