There are two types of explanatory reports: a Procedure Explanation (which is a 2nd Person Instructional Report), and a Process Explanation. These reports do not give opinions, only the explanation on how to do something or how something is done.
A Procedure Explanation directly tells how to perform the steps, using the second-person you, whereas the Process Explanation explains how the steps are/were performed, using either the first-person I / we, or third-person he/she/it/they.
Procedure Explanation/2nd Person Instructional Report
As an example, if I were stranded on the interstate with a flat tire and needed to know how to change it, I might call you and you would give me step-by-step instructions that I would need to follow. This would be a Procedure Instructional Explanation, using the second person (understood you):
1. Open the trunk.
2. Remove the jack.
Process Explanations can be classified into three categories: Processes in which people are the agents of the action; Processes in which machines are the agents of the action, and Processes in which nature is the agent of the action. These reports are referred to as Third Person Instructional Reports.
Processes by People
If I knew you had been stranded on the interstate, I might ask how you fixed your flat tire. You would tell me step-by-step how you did this (using the first person I), but never expect me to do it.
1. I opened the trunk.
2. I removed the jack.
I might ask you how cars are assembled. You would tell me step-by-step how this is done (using the third person, they), but never expect me to do it.
Processes by Machines
You may need to explain how a fax machine works. You would explain step-by-step how this machine works (using the third person, it).
Processes by Nature
You may explain beach erosion, explaining the step-by-step process (using the third person, it).
Note that headings, subheadings, and visuals are important in instructional reports. Procedure reports (2nd person Instructional reports), will have major steps, followed by a sub steps and markers. Process reports will have headings, subheading, and markers. Both reports will have visuals.
See the following example:
OER Example 2nd Person Instructional Report: https://s3-us-west-2.amazonaws.com/oerfiles/technical+writing/Example+2nd+PERSON+Meter+Review+and+Update+Procedures+with+Notes+2.doc
(Note major headings that categorize the steps into 5 major categories, with each major category followed by its steps and sub steps.