Where did Dr. Frankenstein get the body parts for his monster?
In Chapter Three, Victor says that he "began the creation of a human being." In order to achieve his goal, he requires "lifeless matter" so that he can "renew life where death had apparently devoted the body to corruption." In other words, he needs body parts, and so he must look in all of the places one might find those parts: the morgue (the "charnel houses" later referenced in chapter four), slaughter-houses, etc. He also says, in Chapter Three, that he "dabbled among the unhallowed damps of the grave [and] tortured the living animal to animate the lifeless clay." Thus, it sounds as though Victor actually did resort to digging up fresh graves in order to plunder the bodies buried there.
Importantly, it is in his "pursu[it] of nature to her hiding places" (the morgue, the grave, and other similar places that the average human eye avoids) that forces his "human nature to turn with loathing from [his] occupation" (chapter three).
In Chapter 4 we see that Victor Frankenstein has an increasing fascination with death. He tells us he has never been afraid of or superstitious about graveyards, and he has become obsessed with finding out how and why death occurs.
This is the chapter where he explains that he has decided to create life and details how he went about it. To obtain the body parts he frequented a few places. First, he tell us he "collected bones from charnel-houses." According to the Oxford English Dictionary a charnel house is "a house for dead bodies; a house or vault in which the bones of the dead are piled up." You can think of "charnel houses" as another term for "morgue."
The charnel houses were not his only stop, however. He tells us later in Chapter 4, "The dissecting room and the slaughter-house furnished many of my materials." We can assume by this description that he was not only obsessed with finding body parts, but very resourceful!
"To make his creature, Victor Frankenstein "dabbled among the unhallowed damps of the grave" and frequented dissecting rooms and slaughterhouses. In Mary Shelley's day, as in our own, the healthy human form delighted and intrigued artists, physicians, and anatomists. But corpses, decaying tissue, and body parts stirred almost universal disgust. Alive or dead, whole or in pieces, human bodies arouse strong emotion--and account for part of Frankenstein's enduring hold on us.
In Mary Shelley's Frankenstein, the main protagonist, Victor Frankenstein, built a humanoid creature in the lab and (quite literally) gave it life and called him the Monster. This creation was built from human body parts, but it was much larger than an average human being and stood at over eight feet.
Dr. Frankenstein got the body parts he needed to make the Monster from dissecting rooms, slaughter houses, graves and morgues. He collected the bones, necessary for the work, from charnel houses. Much of this work had to be done at night, because stealing body parts from graves is abhorred in a civilized society.
Whether he made the creature from whole body parts (one leg here and a hand there, etc.) or used the stolen/procured body parts in some other way is not very clear from the story.
He went through people's graves to find body parts. He dug up freshly made graves and dissected them for the limbs he desired. He had to do this in the secret of the night because, generally speaking, stealing from graves is frowned upon in many societies including Victor's society.