Just was reading about bars on some other forum. Just want to know more in depth about this  along to the lines of the bars for the Intro, chorus and hooks section of a beat. Just was reading that you change the pattern for each part of a song. Just like to have this explained and cleared up a bit for me which would be thankful

A bar is 4 beats of music. The various parts of a song have changes to make them different, in hip-hop sometimes the beat doesn't have specific changes, it's up to the MC to dictate where they are.

The basic parts are: Intro, Verse, Chorus

Intro is the build up at the beginning of the song. Verse is where most of the lyrical content is and Chorus is where the refrain or hook normally is.

Lets say you're talking about "In a Club", The intro is where 50 is saying "go shorty, its ya birthday.." The chorus is where he sings "You can find me in the club, bottle full of bub,..." and the verses come in between the choruses where he raps all the other stuff..