The paper in BMC Medical Research Methodology gives practical step by step guidance on writing your discussion section.
Hofler M, Venz J, Trautmann J, Miller R. Writing a discussion section: how to integrate substantive and statistical expertise. BMC Medical Research Methodology. 2018, 18:34. DOI: 10.1186/s12874-018-0490-1. Available in html format or PDF format.