Ok kiddo, so the British government wanted to go into Iraq, but they needed permission from a special group of people called the Parliament. The Parliament is made up of lots of different people who work for the government and they all had to vote on whether the government should be allowed to go into Iraq or not.
Now, before the vote, there was a big argument between people who wanted to go into Iraq and people who didn't. Some people thought it was a good idea to go into Iraq because they believed that Iraq had weapons that could hurt people. But other people didn't think it was a good idea at all. They thought that going into Iraq would start a war and hurt a lot of innocent people.
So, when it was time for the vote, the Parliament talked about all of these things and then each person had to make a decision. They all had a little button in front of them and they had to press it to show whether they wanted the government to go into Iraq or not.
In the end, more people voted yes than no, so the government was allowed to go into Iraq. But some people still didn't think it was a good idea, and there were protests and arguments about it for a long time afterward.