create a If statement

I am trying to do a if statement, example:

If this is homepage, SHOW THIS if NOT Do Not Show This.

the goal is to only show certain things on the homepage and add certain things on posts and pages.

I do not like the fact that the sidebars can not be edited and always are consistant, is there a way I can adjust this?

from my last CMS I had easy php if statements to help me adjust what shows on what page.

I can not find the answer anywhere, I see that it is possible as I see if statements within wordpress, but I do not know how to call homepage, post, pages, etc. and inserting the variables

help please