The MATLAB "Getting Started" guide from Mathworks is a good beginning reference, available in
HTML.
Please note that the "Getting Started" guide is not exhaustive--there are many important and useful features of Matlab outside of its scope. Please explore the Matlab help pages (using the help browser, the help and doc commands, the search documentation window in the Matlab environment, etc.) for more about what Matlab can do. And as always, feel free to ask your prof. any questions as well!