There are a couple of major components that are important to understand, when you analyze the results page. These bullet points below breakdown some of the main things to look for on the results page.
File Viewer: The file viewer allows you to cycle through parsed source code files along with highlighted matches.
Match Explorer: The match explorer will display all matches found for the current selected file. Top matches are displayed first along with a similarity score for each particular snippet, then peer matches, and then web matches. Clicking a match will open the file side by side with the match found, if it is a web match you will also be provided with the URL of the web page found.
Probability of Plagiarism predictor: This tool estimates the samples likelihood to contain plagiarism. It will split the peer and web score into separates estimates as well as a combined third one.
Source Makeup: The source makeup pie chart will given an overall estimate of the composition makeup for the selected submission. It includes the percentage of unique content, peer matched content, and external matched content. This is only an estimate and may not be accurate, so you will need to examine in more detail if the percentages seem alarming.