but when I compile it, it says goto.c file doesn't exist
post a full build log. From the build log tab as described here:
http://wiki.codeblocks.org/index.php?title=FAQ-Compiling_(general)#Q:_How_do_I_report_a_compilation_problem_on_the_forums.3FYou have to add the goto.c file to your project so codeblocks can find it. Project->Add file
I have one more question, how do I use the functions for creating boxes on the screen
well I read a program for it which contained a file named goto.c and has functions like gotorc( r,c) and so on
i don't think that drawing boxes is easily possible on modern windows machines.
should I change the compiler I am using or should I change the project like using some other project like there are AVM project etc.
You are good to go with the gcc it is quite standard compatible and ok fast. What is AVM? If you change the compiler as soon as you hit problems you will gonna run out of compilers quite fast. The compiler is never (or at least at your level) a problem, but always the user. And a other compiler won't fix this.
The problem with beginner like you is we don't know how to help you unless you learn the right wording. You talk about libraries but mean only additional c files. You talk about the standard library and you even don't know what the std library is... If we read your post we think over complicated and begin with complex concepts and this will intimidate you even more...
So to create a library like i think you mean (aka using multiple c files) you simply add the second c file to the project. Or even more simply you go to File->New->File..-> select source or header file->Go->Next->select "C"->Next->Press "..." and select the save folder for the file. It is convenient if the file is in the same folder as the project, select "All" targets->Finish
Now you can enter the code in this file. You will need a c and a h file to be able to move your function to the new source file. You define the function in the c file and declare the function in the header file. Then you have to include this header file in your main c file. But this is out of scope of this forum. We help you by doing this steps with codeblocks. If you have a compiling problem please post the build log as described in the top link.