Hello! So, you would like to learn more about adverbs of manner? Awesome! Here are two great resources for you.
The British Council has a brief explanation of the topic. The best part of this page is that they have four separate interactive exercises to help you practice! Check out http://learnenglish.britishcouncil.org/en/english-grammar/adverbials/adverbs-manner
English Club has an extensive list of the most common adverbs of manner. Make sure to pay special attention to the words that they put in bold. They are the adverbs of manner that do not end in -ly.