Get the manual from Galaxy Tab | Samsung Tablets (there are different versions for each variant of the Tab -- go to your variant and then click on "I own this"), and copy it to the Tab using USB. Get the Adobe Reader from the market and you are all set!
Can you try Samsungs website and download the manual as a pdf file? You can then save it it on the tab for future reference.
I don't have a Tab, but this sounds like a way to do it.