Figuring out a new library
One thing I've come across with open source Smalltalks is that there is often no formal documentation for a Library.
So, coming from Java and commercial programming, I'm like "where is the documentation and an example?".
In practice, I've found that with GNU Smalltalk, one can expect to find a set of test cases, which give the overall picture on how to use the library and this is enough to get started. The test cases are the examples... maybe this is the case for any well written open source project, I don't know, like I said, my background was using commercial libraries. Feel free to comment.
The next step for me is to browse the classes themselves. Squeak has graphical tools and GNU Smalltalk has gst-doc (generate docs from classes).
To modify a library, since Smalltalk is a dynamic language it may not be initially obvious how it all fits together. The third step can be to run through in a debugger; I've yet to figure out how to use the GNU Smalltalk debugger.