Yeah, it's pretty vague. Victor mentions studying chemistry and alchemy, and when he's actually constructing the creature, he just mentions being surrounded by his instruments. There are comments about galvanism in the novel, which probably led to the use of electricity in the movie.
By far, the most faithful adaptation of Shelley's novel that I've seen is Terror of Frankenstein
, but it's pretty dry, to say the least. It's a fine little movie, and a great companion piece for anyone studying the novel, but it also shows why filmmakers tend to embellish on the story.