merge columns to rows

Hi,
How do I covert multiple rows into few rows of n columns

I've data like this

col1 col2 col2 col4 col5
abc
cde
def
123
321
100
txt
list
xls
1
2
3
4
5
6

Output needed is
abc 123 txt 1 4
cde 321 list 2 5
def 100 xls 3 6

Thanks for the help!
ps

Homework, huh?
At least a couple of ways to do it, what is your teacher talking about these days?
What do you have so far?

Paul,
thanks for the reply.
How do I convert to rows? Can you pl share some examples.
It's part of the analytic functions, I'm trying to understand.
The link provided to DB administration, book seems to be interesting.
Thanks for your time.
ps