She wants to know how to acquire knowledge and act upon it

The commands and prohibitions of Allaah are
to be found in the Book of Allaah and the Sunnah of His Prophet (peace and blessings of Allaah be upon him). The scholars have explained that
in their books, whether they are books of hadeeth or of fiqh. 

Some of the scholars have written books
dealing specifically with the verses of rulings (aayaat al-ahkaam); others have written books on the ahaadeeth of rulings (ahaadeeth al-ahkaam).
Then there are commentaries on these books and texts, such as Ahkaam al-Qur’aan by al-Jassaas; Nayl al-Awtaar Sharh Muntaqa al-Akhbaar;
Subul al_Salaam Sharh Buloogh al-Maraam; Ihkaam al-Ahkaam Sharh ‘Umdat al-Ahkaam. 

The Muslim can find out the rulings, commands
and prohibitions of Allaah in two ways: 

1 – From trustworthy books 

You can refer to the following questions for
more information on the names of trustworthy books: 14082;
20191. 

2 – From trustworthy scholars 

Shaykh Ibn ‘Uthaymeen said: 

There are two ways of acquiring knowledge: 

1 – Acquiring it from trustworthy books
written by scholars who are known for their knowledge, trustworthiness and sound beliefs, free from innovations and myths. 

2 – Acquiring it from a teacher who is
trustworthy in terms of his knowledge and religious commitment. This way is quicker and more reliable for knowledge, because in the first method a
seeker of knowledge may go astray without realizing, either because he misunderstands or because of a lack of knowledge, or for some other reason.
But if a seeker of knowledge combines both methods, that is better and more complete. The student should get his priorities straight, and brief
books on various subjects before studying books that deal with them in detail, so that he will move from one level to another, and he will not
move on to the next level until he has mastered the one that comes before it, so that his progress will be sound. 

Kitaab al-‘Ilm,
p. 64, 65 

With regard to acting upon what Allaah has
revealed, that cannot be done before knowing what Allaah has revealed, So the Muslim must seek knowledge, then when he knows, he must act upon
what he has learned. 

Shaykh al-Islam Ibn Taymiyah said: 

Abu ‘Abd al-Rahmaan al-Sulami said: Those who
used to teach us the Qur’aan, ‘Uthmaan ibn ‘Uthmaan and ‘Abd-Allaah ibn Mas’ood and others, told us that when they learned ten verses from the
Prophet (peace and blessings of Allaah be upon him), they would not move on from that until they learned what was in them of knowledge and
put it into practice. They said, so we learned the Qur’aan and knowledge and practice all together. 

Al-Hasan al-Basri said that Allaah did not
reveal any verse but he wanted to learn concerning what it was revealed and what was meant by it. 

Allaah says (interpretation of the meaning): 

“Do they not then consider the Qur’aan
carefully?”

[al-Nisa’ 4:82]

Considering words is only of benefit if one
understands them. Allaah says (interpretation of the meaning): 

“Verily, We have made it a Qur’aan in
Arabic that you may be able to understand (its meanings and its admonitions)”

[al-Zukhruf 43:3]

The Messengers explained to the people that
which was revealed to them from their Lord, and they had to convey it clearly to mankind. What is required of the people is to understand what the
Messengers conveyed to them, and understanding implies knowledge and action. Whoever knows (the difference between) good and evil and does not
follow good and warn against evil, has not understood. Hence no one can be counted as being a man of understanding unless he does what will
benefit him and avoids what will harm him. So the insane person who cannot distinguish between the one and the other may fall into things that
will harm him and may run away from things that may benefit him. 

Majmoo’ al-Fataawa,
15/108 

Acting upon that which has been revealed from
Allaah means adhering to the commands and obeying them, and avoiding that which has been forbidden, and believing in what Allaah has told us of
stories and seeking lessons from them. 

And Allaah knows best.