Unofficial list of (official) Bitcointalk.org rules, guidelines, FAQ

[EFS]

Sorry if I missed this but , how do I get an avatar ?

If you ctrl+F "avatar" in first page, you'd see.

Q: When will I be able to add an avatar to my account?
A: Once your account is ranked Full Member or higher.

And how do you become Full Member?
You need 120 posts, 120 activity and 100 merit for that.

You should read all other sticky threads as well.

[Bluedrem]

I'm a little bit confused about number eighteen (18) on the forum rules, I have seen some users in the forum get in trouble and some get negative trust for having multiple accounts in the forum, but here it clearly says that it's allowed. I really don't understand it or am I missing out on something? I really need some explanation!

I think those who are having problems are not actually having problems with having multiple accounts. The main reason for their problems may be:
1.  merit farming.
2. Creating another account through one account.
3. Sharing merit among themselves without qualification.
4. Fraudulent signature promotion.
5. Breaking other rules.