How to answer on certain parts of someone's post

[Stig_ProRacer (Stig)]

how do I answer on certain parts of someone’s post?

[sjr04 (uep)]

Do you mean quoting? If so just select the text you want to reply to.

@Stig_ProRacer

I answer on certain parts

[Darkzonian (darki)]

You should complete the tutorial by @discobot. It has everything to get you started regarding the DevForums.