Welcome to the Q&A Forum

Ok, so you are saying your webmaster tool says tons of 404 errors and your Moz account says multiple duplicate titles.... 404s: This will not be easy but you can fix it...all you have to do is to identify all the 404 pages and then the pages that are most relevant to them... use the redirect plug-in and redirect all the 404 pages to most relevant 200 (active pages) pages available on the website. Duplicate titles: For Duplicate Titles all you have to do is to identify all the duplicates and feature update with unique titles accordingly! Note: Usually using a Free WP theme is a shitty idea as they are not SEO friendly and contains tons of development faults! Hop this helps!