There occurs few rules as follows regarding the position of articles in the sentences.
a. The article is placed before a noun to which it belongs.
b. When a noun is preceded by an adjective, the article is placed before adjective.
c. If the adjective qualifying a noun is preceded by an adverb, the article is placed before the adverb.
d. The indefinite article comes after many and after adjectives preceded by too, so, how, etc.
e. The definite article is placed after the adjectives.
f. The definite article is placed after a noun, which is followed by an adjective used as a title.
a. There is a snake.
b. Robert Frost is a famous poet.
c. Today is an extremely hot day.
d. I never experienced such a fine morning.
e. All the books were arranged in a row.
f. Alexander, the great was a great warrior.