Depending on how much you know about coding you can do it yourself on github or you can use one of the many processers below.

DO NOT use SpectroCoin.
https://www.blockchain.com/api/api_receive
https://bitpay.com/
https://www.coinpayments.net/
https://cointelegraph.com/bitcoin-for-beginners/how-to-accept-bitcoins-in-my-store
https://www.shopify.com/bitcoin
https://www.alfacoins.com/?gclid=CjwKCAiAlO7uBRANEiwA_vXQ--YnqJoZ-of5-BMEc4CMb0g4fTGhyfv9NBoz05dfbodGEHUeJ6qA3BoC79MQAvD_BwE

Something here should surely help you. Otherwise, just ask again here. xD