First of all get on the website. If you wanna be lazy just click this link: https://www.sumopaint.com/home/#app
(For paintbrush) On the top you'll see a bar with options. To change the size change the "diameter." (higher numbers=bigger brush, smaller numbers= smaller brush.)
To make it semi translucent (see through) change the opacity.
To change the brush itself click the button labeled "brush." Then it will show you many cool texture options.
There also are layer effects (if you click the arrows next to swatches and advertisement you will be able to see the layers.) To add layers simply click the "layer" button on the top middle.
I made my profile from Sumo Paint which I think is a good example of what you can do on there.
But honestly your most likely a much better artist then me. Have fun and enjoy exploring the program!