Welcome. Congratulations on passing your EMT exam.
Could you please clarify what you mean by your question? Do you mean an EMT bag for your vehicle or to keep at home? Or for work? Your employer should provide you with everything you need while on duty. They are not responsible for what you do or carry off duty and will not provide anything for that.
If you want an EMT bag, commonly called a "whacker bag", there are plenty of commercially produced kits available for purchase. Really, though, the only thing you need is a cell phone with good coverage to call for help.