Bitte schildern Sie den Ablauf schriftlich.

English Translation

Please describe the procedure in writing.

Warum nicht “beschreiben”?

Together with “Ablauf”, “schildern” is the more idiomatic choice here. It translates to “to depict”. I would say “beschreiben” is more generic and applies more to things you see, while “schildern” is for something that you experienced, like a witness’ testimony.