Try
myTable=Table[0,{x,8},{y,8}];
For[population=100,population>0,population--,
x=RandomInteger[{1,8}];
y=RandomInteger[{1,8}];
myTable[[x,y]]=myTable[[x,y]]+1
];
myTable
and the result is
{{2,2,2,1,1,4,1,3},
{4,1,1,4,1,1,2,2},
{2,2,2,1,1,1,0,2},
{4,0,0,1,0,0,2,2},
{1,1,4,2,1,1,0,0},
{0,1,1,0,1,2,1,0},
{2,0,2,1,2,3,2,3},
{2,2,1,3,3,3,1,2}}