Gothic literature is a genre of literature that developed from Romanticism in the 18th century, with The Castle of Otranto widely regarded as the first of its kind. The genre has many 'tropes', sterotypes or common features.
Setting: The setting could often be considered 'wild', for instance the Yorkshire moors in Wuthering Heights or the Arctic tundra where Frankenstein and his monster end up in Frankenstein. Alternatively, imposing medieval castles can form a basis for the novel or story, as is the case in the eponymous story in The Bloody Chamber and other stories by Angela Carter, The Castle of Otranto by Horace Walpole or Dracula's home in Dracula - which also receives bonus points for starring a ruined abbey at night!
Also, take note of the weather. These wild places often have wild storms, mirroring the characters situation - for instance, in Macbeth Scotland suffers from horrendous storms as Macbeth's tyranny and Lady Macbeth's insanity spiral out of control.
The supernatural: A core part of any gothic novel, there are two ways of handling it. Ann Radcliffe pioneered the explained supernatural in which the supposedly supernatural goings-on of her novels are resolved in a 'normal way' - this is parodied in Jane Austen's Northanger Abbey in which a 'silly' young girl mistakenly believes her friend's father to have locked away his wife.
Alternatively, the supernatural is real. This is evidenced in many, many novels and stories: the witches in Macbeth, the creation of life in Frankenstein and vampires in Dracula and Carmilla.
The antihero: The antihero is a commonly employed device in gothic literature. An antihero is a main character in a novel who does not have the typical heroic attributes. One example is Heathcliff in Wuthering Heights, as he is depicted as cruel and veangeful (not heroic characteristics).
The femme fatale: A femme fatale is a female character, typically beautiful and seductive, who manipulates the male characters into doing her bidding. Lady Macbeth could be considered such a figure, as she manipulates her husband into killing the king which ultimately brings about their downfall.
Angela Carter subverts this trope in her feminist collection of short stories: in The Lady of the House of Love, the vampiress is sad about her succubus nature and need to kill young men to survive.
Religion: Many gothic novels challenge the nature of religion, or at least question it. A prime example of this is Frankenstein, in which Frankenstein becomes God-like in that he manages to create life, but he is then horrified by this act (which could be considered as his horror at challenging or defying God). Frankenstein's monster also reads Paradise Lost later in the novel and sympathises with the Devil, having knowledge of what it's like to be abandoned by his own creator.
In conclusion, there are many different themes and tropes common to gothic literature. Hopefully a few of these will be familiar to you, but there are many many more, such as the innocent and virginal damsel-in-distress, insanity, framing the novel e.g. with editorials and unreliable narrators. See if you can figure out some of these in relation to the books you're studying.
NB: Unfortunately, I didn't have the books to hand whilst writing this so I wasn't able to analyse any quotes. I will update it if I can, but if not I'm happy to go over them with you/do another post about it.