how is hydrogen created in a lab?

Industrially, hydrogen gas is made using two methods, usually one after the other. In the first reaction, called steam reforming, methane is reacted with water to form hydrogen gas and carbon monoxide.

CH4 + H2O → CO + 3 H2

There are other ways to make hydrogen gas in the laboratory, for instance adding a reactive metal, such as zinc, to an acid, or adding an alkali metal or alkaline earth metal to water (although that is explosive!), or through the electrolysis of water.

Electrolysis of water is probably the easiest way to create hydrogen in a lab. Note that you are not really creating anything. Hydrogen and Oxygen are chemically bonded to form water, H2O. This uses electrical energy to break the bond, producing Hydrogen gas and Oxygen gas and heat.

Partially fill a glass container with water. Pure water will not conduct electricity, so add a little salt.

Connect the positive terminal of a battery to one metal strip and the negative terminal to another metal strip. Submerge the strips in the salt water solution. You will observe gas bubbles coming off both strips. The bubbles coming off the negative strip are hydrogen gas. The bubbles from the positive strip are oxygen.

Be careful the combined gasses called Brown's gas are very explosive.