The following are "best practices" for getting a quick (and correct!) response to a post:
1. Use a good Subject line. "How to Extract a Submatrix" is better than "Newbie Question."
2. Use simple language. You might be an expert in nonparametric statistics, but other readers are not. Explain your problem so that a reasonably smart person can understand.
3. Include example data. Either include a DATA step, access data from SASHELP, or define a SAS/IML matrix or vector.
4. Describe the operation that you want to carry out. Saying "I want output that looks like this..." (give example) is often extremely helpful.
5. Post any example code that you've tried, even if it doesn't quite work. It helps to see the shell of an attempt.
The SAS-L discussion group lists other ways to post good questions:
http://www.sascommunity.org/wiki/SAS-L
There is also a nice SUGI paper by Howard Schreier:
http://www2.sas.com/proceedings/sugi29/247-29.pdf
Any other tips or links? Post in the comments.