If you are very new to medical statistics, you may register the course 'Introduction to Systematic Review and Meta-analysis' for free in Coursera. The course is taught by Bloomberg School of Public Health at Johns Hopkins University. It will help you to get some understanding on how to perform and interpret meta-analysis.
Please see the links below for details about meta-analysis:
https://peerj.com/preprints/2978.pdf
Article How to do a meta-analysis
If you are interested in conducting mete-analysis for mean difference (one of the size effect in meta-analysis) then please see my paper on the link below:
Article Improved Hydrological Projections and Reservoir Management i...