Shiva asked in the lessons about the difference between could and could be.
Could is what we call a modal verb:-http://www.learnenglish.de/grammar/verbmodal.html
Click on the link and you will see it can be used in a variety of ways, and that could be why people get confused.
Did you see what I did there?
"Could be" can be used to express the possibility of something being true (or not).
For example: This could be the next forum.
It can also be used to describe the way something / someone behaved in the past:-
For example: As a child I could be a pain in the neck. / My first computer could be very temperamental.
Shiva, if you read this, the best thing to do now is practise a few sentences here.