Please give me some advice (´－ω－)人

I'm starting a new job.. anyone got any advice on how to behave and be like during the probation period in an office setting ?? Until now I only ever did work from home jobs.. so I don't actually know how to be professional in a work setting.. and act confident so that I won't get picked on or become a doormat for seniors .. any advice is welcome
(´－ω－)人