Please help! Urrrgggghh!!! Watch

The psychodynamic approach model assumes that mental illness is a result of psychological rather than physical forces, and are the result of unresolved unconscious traumas from early childhood.

background~ (which you probably already know)
Id-irrational please seeking part of the personality (present from birth)
Ego-rational conscious part of personality, develops due to environmental interactions (present from 2)
Superego-moralistic part of the personality, seeks to block the unacceptable urges of id (present from 5)
The Id and the superego ate constantly in direct conflict with each other and are managed by the ego, who copes by allowing each to express themselves at appropriate times (e.g. id might want to snatch a toy, superego would know it's wrong, ego may attempt to share the toy as it balances the desires of the id with the guilt of the superego)

Mental illnesses:
During childhood, the ego isn't developed enough to deal with severe conflict or trauma and so if it occurs then either the Id or superego will take over the psyche
e.g. If someone ends up with an overdeveloped superego, they may develop anxiety disorders due to the superego feeling constantly guilty and in the wrong
if events like this happen where trauma is apparent, the brain will deploy defense mechanisms to try and counter this
e.g. (carrying on with the anxiety example) repression may be used to counter this. This is where threatening thoughts are hidden deep in the unconscious mind in order to try reduce the anxiety. However these may emerge later as abnormal adult behaviours.

The psychodynamic theory also covers frauds theory of psychosexual stages but I don't know if your exam board covers that but it may be worth a look at anyway.
(Tbh om not sure what exam board I'm on but I am currently studying AS psychology this year)
Hope this helps in any way