Welcome to MR, afterry, and what a very nice brother you have. Since your brother has already had experience with the Sony 505, he will be a great help to you for getting started (even though he says he won't... siblings are like that
).
Below are a few links that may be of interest to you as you learn.
You can explore using
Calibre and Kovid, the creator, frequents the forums here. We even have a dedicated
Calibre forum.
Did you know that MR has free ebooks? They have been beautifully handcrafted by some very dedicated MR members.
ePub format and
Sony BBeB / lrf format
Free ebook sites ...
feedbooks.com and
manybooks.net
Free and for purchase ebooks
smashwords.com
baen.com
Plus Baen has a
great free library
We have a
Sony Reader Troubleshooting Guide (in the
MR Wiki) that is being put together by members (just in case you have some of those problems
) also in the MR Wiki is information on your
Sony 600.
There is also a
How to download ebooks from the MobileRead Library thread that was just started.
Have fun exploring the forums and ask if you have any questions.