Use the past simple with a finished time such as yesterday. Use the present perfect when a present connection matters and no finished past time is specified.
Practical examples
I sent the email yesterday.
أرسلت الرسالة أمس.
I have sent the email, so you can read it now.
أرسلت الرسالة، لذا يمكنك قراءتها الآن.
Have you finished the report yet?
هل أنهيت التقرير بعد؟