The Rape of the Lock is a mock epic, meaning that it is written in the form of an epic poem but uses satire to make fun of the society in which Pope lived. Pope saw this society as one which had exalted the trivial matters of life to the highest honor, the exact opposite of ideals the heroes in The Iliad stood for and fought for. The whole poem is an extended metaphor in which Pope compares the great epics and their heroes to this trivial society. An extended metaphor is one which runs throughout a whole piece of literature. Belinda's clothing and jewelry are her armor and weapons. Her curls are the trap, love's labyrinth, she sets for her enemy, the man who would try to take advantage of her. Her petticoat is the battlefield where her chastity must be protected at all costs, described as a defensive armament much like Achilles' shield. These metaphors are used in the second canto if you wish to go back and reread them.
It's been awhile since I've taught this, but I do remember these particular examples. Please let me know if you have further questions.
Sol thro' white Curtains shot a tim'rous Ray,
And op'd those Eyes that must eclipse the Day;
The "white curtains" are clouds. Sol is the sun, shining through the white clouds.
And now, unveil'd, the Toilet stands display'd,
Each Silver Vase in mystic Order laid.
First, rob'd in White, the Nymph intent adores
With Head uncover'd, the cosmetic Pow'rs.
A heav'nly Image in the Glass appears,
To that she bends, to that her Eyes she rears;
Th' inferior Priestess, at her Altar's side,
Trembling, begins the sacred Rites of Pride.
Unnumber'd Treasures ope at once, and here
The various Off'rings of the World appear;
From each she nicely culls with curious Toil,
And decks the Goddess with the glitt'ring Spoil.
This Casket India's glowing Gems unlocks,
And all Arabia breathes from yonder Box.
In the section above, the young girl awakes and gets ready to put on her makeup and do her hair. There are several metaphors in this passage - the heavenly image is the young girl herself; the "inferior priestess" is her servant that is going to help her put on her makeup and arrange her hair; the "treasures" are the makeup and perfume bottles; the Goddess refers to the girl again, etc.
But when to Mischief Mortals bend their Will,
How soon they find fit Instruments of Ill!
Just then, Clarissa drew with tempting Grace
A two-edg'd Weapon from her shining Case;
So Ladies in Romance assist their Knight,
Present the Spear, and arm him for the Fight.
He takes the Gift with rev'rence, and extends
The little Engine on his Finger's Ends:
This just behind Belinda's Neck he spread,
As o'er the fragrant Steams she bends her Head:
Swift to the Lock a thousand Sprights repair,
A thousand Wings, by turns, blow back the Hair,
And thrice they twitch'd the Diamond in her Ear,
Thrice she look'd back, and thrice the Foe drew near.
Can you guess what the metaphor is in the section above? It is the scissors with which the young man is going to gut off the girl's hair (the "weapon").
Now, see what you can find. The best way to pick out metaphors is to read a section, ask yourself "what is he talking about here" or "what is he describing here" and then look at the language to see what images the author uses to describe a person, thing or event. Since you know the basic outline of what happens - a young man is going to "steal" a lock of a girl's hair - you can look for poetic ways the author expresses the action. With metaphors, a poet uses other words or images to express these ideas, so the reader gets a picture in his mind. Remember that a metaphor is a comparison.
See the analysis here on enotes.