I am assuming your Tree Fern is not in a pot currently, and you've bought it just as a "log". Pick a shady spot that isn't dry - dig a hole, insert the log bottom end down 6 inches into the soil for stability, backfill and firm into the hole. Remember you must water the crown regularly, or spray the trunk, because this is where most of the roots are. If you want it in a pot, and it's very short, insert 3 to 4 inches into the compost and wedge pebbles around to keep it upright.

And remember that the New Zealand Tree ferns are less hardy than the Australian Dicksonia antarctica so may be best in a pot to move inside during the winter.