Blast-Help

[krishnan at BORCIM.WUSTL.EDU]

Hi folks,
I sequenced a 3 kb piece of human DNA and wanted to see if it has homology
to the database.  A colleague suggested that I do "Blast", which I did by
 email.  Now, I need to interpret the output.  Would somebody help me
undertand the following?
	(1) What do the "highest scoring extension..." tell?
	(2) In the portion containing "sequences producing high-scoring
segment pairs, what is the meaningful "cutoff" score?
	(3) How to interpret the column "smallest Poisson probability"?
(Sorry, if this sounds too basic.  I still don't have a good grasp of the
Probability equations!).

I shall be glad to post a summary of responses.
Much appreciated,
Regards,
Raja
email: krishnan at borcim.wustl.edu