is form I-129 the one to file for H1B extention?

[wouldliketoknow]

I am trying to figure some things out. Even though it seems the question is too silly, when one spends an insane amount of time thinking about things, nothing is quite certain anymore. I would appreciate if you confirmed it for me.
Also, what exactly are the documents needed for filing H1B extention? Thanks so much in advance!