You may want to recompile the module for some reason. On Windows there is a compiled distribution. On Linux we may later provide packages. The current version of ScriptBasic v1.0b18 does not support Linux packages. If you try to use the GD module on UNIX you have to compile it.
To successfully compile the module and get the .so file you have to install the zlib and libpng packages. These are free source code programs that you can download from
GD source code from http://www.boutell.com/gd LIBPNG source code from http://www.cdrom.com/pub/png ZLIB source code from http://www.cdrom.com/pub/infozip/zlib/
The Windows source package ZIP file includes the non-debug version of libraries needed to link the module GD. The source file for the GD module is gdinterf.c. The Windows source package also contains the include files from the gd C package that are needed to compile the ScriptBasic interface.