It is very complicated to me, I have one other coin in Waveswallet but do not know how to transfer it in waves coin.
It's not that hard:
After opening
www.waveswallet.io, you see in the centre 7 icons.
Click on the third from the left: "The Waves decentralized exchange". You will then enter a new tab.
On the right site you see some traiding pairs. Click for instance on MRT/WAVES
In the graph on the left you can now see the price trend of MRT against Waves.
On the right below the graph you see "Sell Miner Reward" and directly behind this the amount of MRT you have got.
Clicking on the quantity puts this MRT number in the "Miner Reward amount" box below and the last price for which MRT was purchased in the other "the price in Waves" box.
If you agree with the price, then click on "Sell" and your order will appear under "My orders" below. If you do not agree with the price, then change the price.
The number of tradeble pairs in the boxes to the right is limited. Most coins are not listed.
If you have an other coin that you want to exchange for Waves, then change above the graph on the left side in the "Miner reward" box for your coin (wait a few seconds, this takes a while. For example, if you want to trade WavesGo, then unfolds as soon as you start typing already a list of choices, which you can choose from).
After this, the procedure is exactly the same again.