I did PE during my Corporate Finance classes. Though the internet is full of resources, I strongly recommend a chapter in a book. It has about 20 pages (well, the chapter has 50, but 20 are essential) - if you still have your uni account, I think you can download it. Drop me a line in private and will send you the book's details once I get back home later tonight.
Although the last thing I'd do is to recommend going into literature, that chapter is extremely concise and spells out what the main business model is, including the overstated risks associated with PE. IMO this resource is the starting ground to cement your understanding. Then, the internet is useful for keeping abreast with commercial developments e.g. the debt market etc, i.e. the fancy "commercial awareness" term.