The first place that you should look for sample personal statements is on the website of the school in which you are attempting to get into. If you can find samples of the admission essays of others who have already been accepted into the school then you can really begin to dig deep and find out what will be expected of you. Depending on the school in which you are trying to gain entry to, finding these samples can be easy or darn near impossible. When the latter happens you can always turn to the internet for help. Just as with anything else these days, the internet has an unbelievable amount of websites with samples of various types of admission essays. You can begin by conducting a Google, Yahoo, or Bing search on 'personal statement examples' and then begin to look at the different results that come up.
Then look at some resources for writing personal statements and get some advice. There are lots of websites which will offer you advice for writing a personal statement but it is best to look at websites from reputable organisations such as UCAS or student advice websites which are well used such as The Student Room. Remember to ask your teachers, friends and family for advice. A good question to ask them is "what do you think makes me different from other people? or "how would you describe me?" because the answers often give you some interesting information that you hadn't thought about. The personal statement is not something you can write quickly so be prepared to think a lot about yourself, your qualities, skills, experience, likes and dislikes. You are unlikely to meet the people who read it so your personality needs to come though on paper; this is difficult.