You should:
1) Download the Big_Game_Fishing.zip
2) Extract (unzip) the file and move the folder that it creates to C:
3) Download DOSBox.
4) Install DOSBox.
5) Run DOSBox.
6) Type:
a -
MOUNT C: C:\ <press enter>
b -
C: <press enter>
c -
RUNME <press enter>
Now the game should start!