Ahhhh the good ol' engineering report XD
So basically from what I learned in prelim in an engineering report you should have have the following: (this is just from the top of my head so it's not a definite guide or anything)
Title Page - should include title of report, school, name etc.
Introduction - just a short intro about the purpose of the report, background information about the items involved , brief detail about method involved and results that were gained etc.
Methodology - The method you'll use to carry out the findings of the report
Results - Basically the results you gathered in your investigation - talk about it in detail
Conclusion - What you've concluded from your investigation in your report, has it answered the aim of your report, restate major findings of investigation - doesn't have to be too long
Acknowledgements - basically your bibliography
There might be some stuff missing but this is basically like an extremely brief guide - you should research some more about each of those headings on Google or something in detail
Hope this helps