Use of articles in these sentences?

1. The error message is displayed at the end of (the) home page.

2. The error message is displayed on the end of (the) home page.

3. The error message is displayed in the end of (the) home page.

Which one is correct? Is the article "the' written in the bracket necessary?

4. Look at both of (the) sides while crossing the(a) road.

Is "the" proper article here or should it be "a"?

5. (The)Error message displayed on (the) home page is wrong.

or this sentence should be, 

5.(Edited) Error message displayed on home page is wrong.

I am confused about the use of articles. Especially, use of "The".

Also, 

Which one is correct from these ?

Clean your table before leaving.

Clean your table before you leave.

I think, both are correct and indicate same meaning.