circuit breakers

I am looking at adding some lights to a kitchen lighting circuit. Iv had a poke around to establish the initial circuit and it's going to be a "leave it to the professionals" job, however, I would like to satisfy my own curiosity and frustration. If anyone would be kind enough to explain I would...

I noticed all of my downstairs lighting blew the fuse last night. As process of elimination I took out all the bulbs one by one to see if that was an issue. It still kept tripping the breaker. Even after all the bulbs were taken out it kept tripping. Went to bed to watch TV not a problem. In the...