Ruth 3:6-9 meaning

Ruth now executes the plan flawlessly. She went down to the threshing floor and did according to all that her mother-in-law had commanded her.  As the plan unfolds, Ruth observes when Boaz had eaten and drunk and his heart was merry. Then after he went to lie down at the end of the heap of grain Ruth takes action, just as Naomi instructed. Ruth came secretly, and uncovered his feet and lay down. Ruth quietly lays at Boaz's feet without him noticing.  

It seems clear that Boaz was sound asleep when Ruth laid down. Boaz did not notice Ruth until the middle of the night. Ruth might have lain there for several hours. It is interesting to contemplate what she might have thought while she waited, wondering what was about to take place. We do know that she stayed there until she was noticed.

Boaz's reacts when he wakes and realizes someone is there. We are told that the man was startled and bent forward; and behold, a woman was lying at his feet.  Boaz asks the most reasonable question conceivable for being startled awake in the middle of the night by someone lying at your feet: "Who are you?" Ruth answered, I am Ruth your maid. So spread your covering over your maid, for you are a close relative.

The word translated "covering" is most often translated "wing" as it is in Ruth 2:12, which reads:

May the Lord reward your work, and your wages be full from the Lord, the God of Israel, under whose wings you have come to seek refuge.

Ruth requests to come under the protection of Boaz. Boaz had commended Ruth for seeking protection under the wings of the God of Israel. Now Ruth requests to also come under the protective wings of Boaz. Her explanation for you are a close relative makes it clear that she is requesting he take her as wife under the kinsman redeemer custom.