Creating a filled copper pour: First select the Draw Polygon tool. Now you will see the poly properties in the top section of the edit panel. Here you can select the type of polygon, line width of a simple polyline, layer, give the poly a name and select a net. I like to start using a simple polyline to create the shape I want. It is a bit easier for me to see when the shape is complete.
Now that you have set the properties for your polygon, you can draw the desired shape. If you have opted to use a filled polygon, the shape will be complete once you return to the starting point with the polygon tool. If you are using a polygon line, once you have completed the shape, return to the select an object tool . Next, right click on the polygon outline and select toggle filled/unfilled. After switching the polygon to filled you will need to assign the polygon to a net if you want a specific net to connect to the fill. You do this by right clicking on the filled polygon then select properties. On the poly properties window select the net from the drop down list and select ok.