What is the Lewis dot structure for N2H4? How is it made?

N2H4 Dinitrogen Dihydride

the first thing we need to do we need to identify the central atom which is usually the element with the highest bonding capacity so we have nitrogen and hydrogen.

Hydrogen we have just 1 valence electrons nitrogen has 5 valence electrons
 The total number of electrons = 2(5)+1(4)= 14 Valence electrons.

Then we need to place a pair of electrons between each adjacent pair of atoms and every two of these dots represents a bonding electron pair that forms a single covalent bond so now we have we need to basically place pairs of the remaining valence electron as known pairs of the surrounding atoms not on the central atom but here since we are dealing with hydrogen as surrounding atoms we need to follow duo’s rule for hydrogen so they need to have maximum two electrons so we don’t place anything on the hydrogen.

Then we need to find out how many electrons are available 14 minus 10 is gonna be four so we need to place these four electrons on the central atoms so we need to place two here as lone pair and two in here as well so now that’s complete we use all the electrons and everything follows the octet rule so hydrogen hydrogen hydrogen hydrogen that’s gonna be the loose structure of N₂H₄.
You can refer to the below video for your reference