I am trying to say I will help someone read a book.
Is this correct?
Sorry if the question is off-topic. I am very new to Japanese and don't yet fully understand how to build sentences larger than very basic ones.
No, that sentence is incorrect for two reasons.
[dictionary form of the verb] + のを助ける.
のhere is a nominalizer, and
あなたが本を読むのmeans "your reading the book", which serves as the object of the verb 助【たす】ける.
The correct sentence would be: