how moral obligation can be derived from the categorical imperative?

According to Kant, the fact that we can consciously do things is because we all abbey hypothetical imperatives, which is a kind of imperative which will reveal the consequences of an action. For example, a typical hypothetical imperative would be ‘if I don’t want to fail the philosophy exam, I must work very hard’. So Kant believes the fact that we are doing things is because we all have these hypothetical imperatives, which is also the reason that makes us rational beings. Kant pointed out that we are having many hypothetical imperatives (which was called maxims by Kant) all the time; for instance, ‘I will starve to die, so I must eat.’ Of cause there are also other negative statements. For example, ‘I don’t have enough money to buy my favourite clothes, so I must steal.’
The reason why we will feel morally guilty if we steal things is because there is also another kind of imperative which is in a higher order so that it can be implied to the hypothetical imperatives in terms of judging it and hence tell the rational beings whether this hypothetical imperative is acceptable.
Thus, Kant concluded his theory so called ‘the first formulation’ which is also known as the formula of universal law’
Act only on that maxim through which you can at the same time will that it should become a universal law.
Kant said in order for a categorical imperative to be implied to the hypothetical imperative and judges it; the hypothetical imperatives must be taken through a process which is so called ‘Universalise’.
For example, for a hypothetical imperative like ‘If I like the book in the store, I should steal it’ after we derive the hypothetical imperative into a categorical imperative, it would be ‘If everyone wants the book, they should steal it’. Apparently, this action is universally unacceptable, because, according to Kant there is a contradiction in this imperative, which is ‘if everyone steals, no one can steal’. It is concluded by Kant that it is called teleological contradiction interpretation, because the consequence is in a dilemma.
So in conclusion, the morally obligations are derived from hypothetical imperative and further judged by categorical imperatives, which are in a higher order, by universalise it. If there was a contradiction in it, it would be morally unacceptable; if however there was no contradiction, the hypothetical imperative would be an acceptable one.