Like many said it will take a while for him to get used to the servers and how to act. Everyone ha been banned before when they were newbies, you should probably look into some of the posts on how to act online, if you search in forum you will find some user-generated rules to go by to help out. Here would be some I have learned an many others also know:
1. NEVER ask or admin unless you either personaly know the host or have a good reason
2. Don't use lolchat talk, you are just fortifying their stereotypes
3. Act mature, don't try to stand out or make a scene
4. No random trust or 'friend invites' there are not friends list and trust is best not to e messed with
5. Watch your language, swearing won't solve anything and just encourae them and get you in trouble
6. Don't take things personaly, it's the internet people, they can live in a whole diffrent country an you will never meet
7. Don't be too gulible, if someone threatens to hack you just ignor them, half the people who play this game are under the age of 16 and don't understand hacking or even what a virus is
8. Don't spam, it doesn't matter who you are, when you first join blockland you probably are horrible at building, build on a baseplate and don't use 1x1's
9. Know the server, if it's an RP don't go around guns a blazing without a clue what your doing, follow what others are doing and try to fit in
10. Watch who you mess with, many people are in a horrible mood and nothing good will come in argueing or fighting with them
*As a side note sorry about the spelling an grammar issues, me being an idiot and the fact I'm typing this on an iPod doesn't turn out well