Hello
I need to find a value and then copy adjacent cell to another cell
then compute simple calculation.
since I am a begginer, I don't have any clue where I have to start
with.
please, help me out.

The idea is when I select on a cell (Column E) it find same value in
Index row (Column A), then
copy the value of adjacent cell (Column B). I'll like from there to
look up two values (Col_C and col_D) to compute which
cells are related, then put the result to last column.

If so, here's what I would really like to do:
Col_A Col_B Col_C Col_D Col_E
1 1980 0.15 -0.35 9
2 1981 -0.14 -0.35 9
3 1982 -0.57 0.05 1
4 1983 -0.57 -0.49 4
5 1984 -1 -0.32 16
6 1985 -0.57 -0.43 13
7 1986 -0.77 -0.07 2
8 1987 0.9 -0.33 16
9 1988 -0.27 -0.45 6
10 1989 1.27 0.07 1
11 1990 0.67 0.08 1
12 1991 -0.145 0.05 1
13 1992 -0.41 -0.45 6
14 1993 -0.77 -0.10 9
15 1994 -0.41 -0.36
16 1995 -0.27 0.05 1
17 1996 -0.15 -0.36 9
18 1997 -0.27 -0.02 2
19 1998 0.23 0.42 21
20 1999 -1.3 -0.78 14
21 2000 0.23 -0.21 18

Say col_E1=9, then when the macro starts, search for 9 in Col_A (say
it's found in A9),copy
the value (1988) of adjacent cell (say it's found in B9), then compare
adjacent values
(adjacent value of col_B9 (1988), -0.27 and adjacent value of
col_E1(9), -0.35).
If Col_C Col_D, then compute Val=Col_c/Col_D, else compute
Val=Col_D/Col_C.
Finally, I put the result in Col_F with format "Col_B*Val", so the
result value of Col_F1..ColF3 corresponding to Col_E1 ..Col_E3 should
be followed.
Col_F
1988*0.77 (here, 0.77=-0.27/-0.35)
1988*0.77 (here, 0.77=-0.27/-0.35)
1980*3.0 (here, 3=0.15/0.05)
....

thank you