Find multiple values in excel coulumns then copy into mail merge

I am an insurance underwriter. I have a monthly
spreadsheet of well over 10,000 lines. It lists all the
agencies our company has and each policy each agency has.
Each agency is assigned a code number. Each policy has a
number.

I have a two fold problem I do not know how to do:

1) Each month find my 20-something agencies based on code
number (and the accompanying many hundreds of lines of
policies), discard all the other lines, then

2) select certain cells from each line to "mail merge"
into another Excel sheet (This second excel sheet
receiving the data can be converted to a Word document if
needed).

Manually doing this every month by cut & paste is too long.
I can highlight & erase all those agencies that are not
mine, but this is too slow and only is part 1.

I'm a "toddler" in Excel, know enough to ask for help, but
do not know the terminology well. Still learning.
Please use low-tech speak!
Many Thanks
Tom