"What's my coin worth" is not an easy question to answer without some specific details. Anyone can jump on the Internet and Google the specific coin they are looking for and get a general value for their coin but to be specific, several facts need to be known and discovered.
There are tools both online and in books to help a person find out the approximated grade of their coin. Websites and even applications for smart devices are available from third party coin grading services like PCGS and NGC that show detailed images of coins in various states of condition or grade that one can compare to the coin that they are holding. You can visit their websites and download their applications to you smart device to access these tools and references.
To get and exact price on a coin, consult a professional coin dealer or numismatist who can help you find the grade of the coin and aid in your research. Graded coins from third party grading services are easier to sell and trade because these services are trusted throughout the industry and take any guesswork out of the equation. Meridian Coins can submit your coins to be graded and help you get the most money for your coins.