unfortunately its a little more complicated than that
you could try the dishpointer site
http://www.dishpointer.com/
Put in your location and pick the Astra 28.2e sat and you may be able to align the dish if you can access it easily
Bearing in mind its not a great time to go climbing a ladder in the dark and on doris day

But keep in mind that being out by as little as an inch with your alignment can make all the difference
small movements is the key
I Would try horizontally first just small movements left or right
get someone to look at the signal meter built in
I know its not that accurate but better than nothing
Good luck