Theory:

Orion:
This magnificent constellation can be viewed clearly at night-time (late evenings) of winter.  The Hunter is another name given for this constellation.
 
orion hunter.png
Orion constellation
 
This comprises seven or eight stars, out of which three stars in the middle is like a belt of the hunter. The other four bright stars form a quadrilateral shape.
 
Orion_constellation_with_star_labels.jpg
Shape of Orion constellation
Sirius:
Sirius is the brightest star which is located close to Orion in the sky.
 
sirius from orion.png
Position of Sirius from Orion
 
As shown in the above picture, a straight line is passed through the three middle stars of Orion. The line moving towards the east will lead to a very bright star, Sirius.
Cassiopeia:
Cassiopeia is a constellation which can be seen during the early part of the night in the wintertime. It is clearly visible in the northern sky, like a distorted English alphabet \(W\) or \(M\). People in the olden days compared this constellation to the shape of a seated queen.
 
CassiopeiaCC.jpg
Cassiopeia constellation
Leo Major:
Leo, meaning 'Lion', is a constellation visible during summer in the early part of the night. It is one of the oldest constellations consists of nine bright stars. It can be viewed from the Northern hemisphere as well as the Southern hemisphere.
 
Leo_Constellation.svg
Leo constellation
Facts about constellation:
Largest constellation - Hydra
Smallest constellation - Crux
Reference:
https://upload.wikimedia.org/wikipedia/commons/thumb/c/c9/Orion_%28constellation%29_Art.png/624px-Orion_%28constellation%29_Art.png
https://upload.wikimedia.org/wikipedia/commons/9/91/Orion_constellation_with_star_labels.jpg
https://upload.wikimedia.org/wikipedia/commons/2/2d/Leo_Constellation.svg
https://upload.wikimedia.org/wikipedia/commons/c/c1/CassiopeiaCC.jpg
https://upload.wikimedia.org/wikipedia/commons/9/9f/Orion-guide_dark.svg