This site has clearly written step-by-step instructions for making a homemade Jedi robe and tunic. It explains very well how to customize the size so it will fit you correctly after assembly.
Here is a site that instructs you on how to make a very authentic Jedi Robe and costume. It walks you though making the robe, outer tunic, inner tunic, belt and more. It even has a quick low budget option.
This site has good instructions on how to make a Jedi costume with Robe, inner and outer tunic, obi and tabards, and more.
