Ok.. to learn C-99 (which Pelles C supports with a few extensions) google is your best friend. There are tons of C tuturials and e-books on the web... you can start
HERE but there are lots more.
Your best bet is to work through whatever instructional material you use, page by page, exercise by exercise... actually type up and compile the code, work with it, break it, fix it, modify it until you understand what does then doesn't work... then move on to the next page. From experience, simply reading material this technical doesn't get it to sink in... you have to work with it.
If you are bent on using Pelles IDE (POIDE) with a C++ compiler you may find
THIS interesting.