Which topics / contents re you to teach within each level? Are those already defined, or are those to be defined by you?
If the topics have already been chosen, you just need to see which language exponents should go with each level.
But if those haven �t been defined, then this is how I think you should go:
The first thing you have to do is see who you will be teaching to - children? Teenagers? Adults? Work-based students? False beginners? A specific professional group? ...?
Having that defined, I think you should then go for contents - what will you be teaching? If you have a non-defined group of students (e.g. - random teenagers practising their English skills during summer holidays), you may choose the topics you consider most interesting to them / most adequate to practise each of the language levels. But if you have any specific group (say, a class of health care workers, or a group of people working on tourism), then you should try to focus on contents that are particularly relevant for them (e.g, - health care workers would need to practise interacting with patients; people working on tourism would probably need to deal with indoor/outdoor activities, ...).
Next to that, I think you would have to define the levels (what each group should be able to do at the end of your course); for guidance, you could take a look at the European Framework of Reference fotr Languages or at the Cambridge English Language Assessment.
For what language exponents are. you may take a look at:
http://myonlineenglishtutor-co-uk.blogspot.pt/2012/09/tefl-functions-and-exponents.html
The European Framework of Reference for Languages (EFRL) is available in:
http://www.coe.int/t/dg4/linguistic/source/framework_en.pdf
(Criteria for descriptors for Common Reference Levels are dealt with from page 22 to page 42)
Cambridge English Language Assessment deals with the correspondance exams - EFRL here:
http://www.cambridgeenglish.org/exams/
I hope this helps you to get started!
