On the tooblar, click the green button to go to the Curver feedback page. It's the purpose of this beta release!
Round Tool Selector
Right-click on the canvas to bring up the round menu tool selector. This allows you to quickly switch between tools while working on your document.
Using the Tools
On the Tool Settings window, some tools will have an icon (i in a circle) at the bottom that can be clicked to show a window containing short instructions for using that tool. Make sure to read the instructions for each tool at least once. They are short.
The Layers window contains a special layer for the background. Use its controls to specify the background image (usually the sketch you want to do line-art for)... etc.
Selecting curves (using the Selection Tool) allows you to specify which curves will be affected when using the Manipulator Tool.
The button-linke controls used to change numerical values are click-and-drag controls. Drag up or to the right to increase the value, down or left to decrease it. Right click to reset to default (if it has one).
Here is a tip: assign a "Spring Shortcut" to the "Activate Selection Tool". Now when using the manipulator tool, you can press that shortcut to switch to the selection tool, select the curve(s) you want to work on, then release the key to get back to the Manipulator Tool.
Review the Curver Workflow
to see which features are being worked on, which bugs are being fixed... etc. If something is not in there, kindly let us know on the feedback page