Assuming that you have all your tokens in your waves wallet, Waves DEX would be the best exchange to use (
for me atleast). You have 2 options to access the DEX, either you download the desktop version (
Windows, Mac OS, Linux) or you use the online client. Both can be seen here
https://wavesplatform.com/productAll you have to do is restore your account using your seed to access your balance and directly trade it. To be easier for you, here's a detailed guide from wavesplatform on
How to trade tokens on the DEX, just read it carefully/understand the process and you will be good to start trading on DEX.