幫幫手..中譯英

I once held a post in xx department of xx Company. From 2000 to 2006.

我曾經任職在xx公司的xx部門.由2000至2006.
英文應該怎樣講
I once held an office in xx company's xx department.
By 2000 to 2006.

I had been working in xx department of xx campany, from the year of 2000 to 2006.