So I don't come off as a
complete ass(I'm an incomplete ass).
You're trying to learn something simple like placing tiles from a script that does way more, thus, is a lot more complex and can mislead you. What you posted serves more than to just lay tiles down, it also is used to calculate what specific tiles to place and where, to generate a path(though it doesn't do all that in the bit you posted, it's written to do so). It's all very complex.
If you have the array of the bush already, which would be 4 tiles, you could do something like.
PHP Code:
for (i=0;i<4;i++) {
tiles[mousex+i%2,mousey+int(i/2)]=bushtiles[i];
}
updateboard mousex,mousey,2,2;