I have a little skills on BASIC and asm code for 6800, but I know nothing of C.
Well then, you need to do a C tutorial. As you already know how to program, picking up another language is reasonably easy.
Google "C++ tutorial". Run through the lessons - the first half, anyway. The second half will be stuff about classes that you don't really need to know yet.
Then google "how arduino programming differs from regular C programming", or something like that. You will learn that there isn't really a cout, not to overwrite main(), and not to use C++ Strings.
Then have a look at the examples in the file menu of the arduino IDE.