When you enter a report on the Review Errors tab, you'll get a breakdown of all locations of errors and warnings. Note that errors are sorted into their chapters, which can be expanded/closed by clicking the arrow next to the chapter. There is a hyperlink in the Source column. You can follow this to the page with the issue.
Note that whenever you follow the link to the page, in the URL field of your browser, the page named will be appended with "#line-X", where "X" is a number. This tells you exactly where the issue is located. Look through the code panel to find that line number, and solve the issue.
Depending on the report type, you might find information around affected content. The last column, Description, will offer information around the cause of the error.
Remember, Warnings will not stop a project from building but merely indicate that there is some inconsistency that you might want to address. Warnings can be a great tool to look over before you release your content to ensure that all of your links are working and that you are not using any placeholder images. Errors, on the other hand, are issues that need to be resolved before the build will complete successfully.
Still having trouble clearing the errors on your project? Contact firstname.lastname@example.org and we'll be glad to help!