You should first have a look at the existing documentation and come back with more specific questions afterwards (if there remain any; but I'm sure there will ;)).
What you want to do is called document preparation in Isabelle. The first place to look is Chapter 4 Presenting Theories of
the Isabelle System Manual. (Actually it is also a good idea to first read the previous chapter on Isabelle sessions and build management.)
For some neat notation also LaTeX Sugar for Isabelle Documents might be of interest.
Some other useful things, like generating TeX snippets from your Isabelle theories and including them in your document (which you might collaboratively work on with others that do not have Isabelle installed), can be found on the Community Wiki.
