I have submitted my adjustment of status application (got married after K1 visa).. and i got a letter saying that i ll have to go there for "BIOMETRICS".

Kindly tell me what is this test all about and what is done in it?

And after that how long it ll take to get my green card and work permit?
And what else we have to do after this Biometrics and finger prints?

Thanks in advance

Thats where they take your fingerprints and collect your Bio ie your biostats info and stuff.

Its not a test as such.

What will happen after this test...and how much time more i ll have to wait???

These Bios are done by the FBI, no effect on your processing times, but you CANNOT be approved until the results come back from the FBI clean.

For processing times, see the USCIS site.

You need to look at them as a way they collect info from you to enable them do a criminal background check on you, to see whether you are a vagabond, criminal who needs to be a persona non grata in the U.S.

Check the processing dates for your local office. That will tell you how long it will be.