Whenever a creature attacks you or a planeswalker you control, reveal the top card of your library. If it's a Forest card, remove that creature from combat. Then put the revealed card on the bottom of your library.
Removing an attacking creature from combat doesn’t untap that creature.
Because Lost in the Woods will trigger once for each creature that attacks you or a planeswalker you control, it’s important to specify which trigger is associated with which attacking creature before revealing any cards.