Tiles[x,y] On Pics1?

[TB3]

Ok question i've reached a brain cramp.
If you need to say, showimg a part of the tileset that replicates a current section of the tiles on ground how would i find the changepart 1,x,y,16,16;
for each tile?
the x and y that is how would i use tiles[playerx,playery] that variable and turn it into an x and y for the pics1?
Or is that possible? I was thinking something on the lines of

y=int(tiles[playerx,playery]/64);
x=tiles[playerx,playery]-y;

But thats not working my god my heads hurting O_O
*Edit*
My wording is probably confusing sorry
How would I turn a tiles[x,y] into a position x,y for the tileset ?
BTW im using new order format which has not much to do with it other than it seems to work different from regular tiles. Pulling up variables and what not O_O