Here's a simple little script which save the game, when the player is touches the object.
Create event of save spot
//variable setup
touch = false;
in step event of the save spot
//check for player collision
if (place_meeting(x, y, oPlayer))
{
//Check touch variable, so it wont run the code again, until you stop touching it
if (touch == false)
{
touch = true;
//save the game
game_save("Filename.extension");
}
}
//When not touching
else
{
//Reset touch variable
touch = false;
}