[quote=@chongjasmine]
I am a newbie when it comes to  play by post?
[/quote]

I don't think this is a question, but welcome to the hobby. 

[quote=@chongjasmine]
How to begin? 
[/quote]

You could look through the Interest check section of the forums and join something that has yet to start, or sign up to an ongoing RP in one of their respective sections. Just post in the OOC if an RP looks interesting to you and you want to know if they are accepting new members.

[quote=@chongjasmine]
What is IC or OOC? 
[/quote]

IC is "In Character" which is where the story posts are posted. OOC is "Out of Character" Where the players/GMs discuss things. If you want to ask to join an RP, you would use the OOC tab. 

[quote=@chongjasmine]
How to roll die? 
[/quote]

https://www.roleplayerguild.com/campaigns

[quote=@chongjasmine]
How to create characters? 
[/quote]

This is RP specific, but it involves filling out a character sheet. You'll need to look at the OOC/Character tab of an RP to see what's involved.

[quote=@chongjasmine]
 What determine their stats/attributes?
[/quote]

See above.

[quote=@chongjasmine]
Is there any book I need to buy?
[/quote]

Usually everything will be in the OOC, but if you join something in the "tabletop" forum, you may be required to buy a book for the game system they are running.