Based on the 25th amendment section 3,how can the president temporarily transfer his power to the vice president

According to Section 3 the president can transfer his powers and authority in a voluntarily way, if he makes a declaration writing about it.

The amendment gives the president the right to resist the removal by asking a vote of both houses of Congress. If the legislature fails to confirm, by two-thirds of the votes, the president's incapacity, he can resume office.

i am confused, what is the question? i can you out if you put it into more depth.