Excel 2007 : Help with excel 2007 editing

Hi guys,
I'm new here and I dont know anything about excel its just that I have to work on some file
here's my remedy what I'm trying work on is editing every column changing the first two words like 98-01 I have to change it to 1998-2001 or 00-10
like 2000-2010 is there any functions that we could use? i'm working on over 2,ooo items.

also, aside from that, at the very beginning of those i have to type in "custom exact fit" in every single of the columns.


please help me I thank you in advance!

here's the sample of the file im working on: