I just figured that Copy & Paste did not exist in Android. I could not find the function at all, even after two years and several Android versions. Well, you can copy and paste from / to many applications.
Here is a link to a good explanation. What they show you works well with a web browser and email, but not on .pdf files (because most .pdf viewers don't let you select text). It does work on Word .doc files.
Basically, you long press on some text...wait a bit and two tab icons appear....move those to the beginning and end of the text you want to select and click on the menu item at the to, "copy". Then go to the application where you want to paste (something that allows you to type in text), long-press in the location desired and an option to "paste" should appear.
Check it out: http://www.androidcentral.com/android-101-using-copy-paste