I run a design firm
and would like to start a service thread in this forum
is that allowed?
if yes which section should i add it in?



Service thread? If you mean advertising, the only appropriate place for your post would be the Post Your Resume forum.

is that allowed?

It's usually wise to ask that question before starting your thread and having it shot down with an infraction. And no, as the infraction PM you received clearly states, advertising your services constitutes spam.