You need to define a grammar for the language (the one for C isn't so big; the one for C++ is enormous). Then you need a compiler that will convert text in that language to object code. You could reuse existing linkers if you followed standards. Otherwise, you'd need to write a linker too so the object code can be converted into an executable program. This step will be repeated for every system type you want to deploy to.
Now, if the language is to be a scripting language then you could just have an interpreter parse the text into a grammar tree and execute it directly from there.
In any case, if you're looking to make a more featureful language than already exists then you have a long, hard road ahead of you.
Also, look into some tools: yacc and bison. They will help with the step of creating a compiler.