"My father is working at a company."
How come it's 'tsutomete imasu' and not 'tsutome masu'? I thought the 'te' was used for imperative? Thanks for any help
The て form has many uses. Among other things, it's used as an imperative, and it's used to link two activities together, regardless of tense. When it's combined with 〜いる, as it is here, it forms the present progressive (~ing in English). つとめています means "is working," which is how Japanese people describe their jobs. In English, we'd simply say "works."
I think generally 働く is more of a blue collar and 勤める for white collar jobs.
No. I put almost the same thing "かいしゃに父はつとめています" and was also rejected. I suspect the issue is the order (office before father), but I don't see why that would make it wrong.