how do i put books onto my kindle that i got from othere people

thanks

I use Calibre: http://calibre-ebook.com/

If they are already in Kindle format just connect Kindle to computer & drag & drop files. As Little_Pob said if in other format, use Calibre.

Connect your kindle to your pc/laptop by the USB lead and the kindle should show up as a hard drive could be E,F or G letter.
Just right click on the books (on cd or pen or your pc)and go down the menu to copy and left click.
Go to where your kindle shows up on your pc left click to open it then right click on documents go down paste and left click it.
or
If you can show in windows explorer a window for the kindle and another for your source of the books just left click on a book and keeping the left mouse held down drag across to kindle
Hope this helps

They MUST be dropped into the folder called "documents"

Here's a handy little computer program for organising your Kindle files.
http://www.kindlecollectionmanager.com/

thank you i did this and it worked thank you.

thank you all for your help