There are a few ways to add vias.
1. You can use the add pin tool to place a via manually at any location. This will create a via that is exposed through the solder mask.
2. A fanout via: To end a trace at a via you can start routing your trace at a pad. When you get to the location you would like to add your via left click and press the v key on your keyboard.
3. Add a via while routing a trace and continue routing on another layer: Start a trace at a pad and route to the location you will need a via. Left click to stop the trace. If you are routing on a two layer board you can press the z key on your keyboard. This will add a via and switch you to the opposing layer to continue routing. If you are routing on a multi-layer board you can use the number key across the top of you keyboard to add a via and switch layers to continue routing.
1 = top
2 = bottom
3 = inner layer 1
4 = inner layer 2
5 = inner layer 3
6 = inner layer 4
You are routing on the top layer and you want to add a via and continue routing on layer 3: Start your trace from a pad on the top layer. Route to the location you will need a via. Left click and press the number 3 across the top of your keyboard. This will add the via and switch to inner layer 1 to allow you to continue routing. Route the trace to the desired end point.
An alternative to using the number key across the top of your keyboard is to use the toolbar on the far right side of your screen. This toolbar works just like pressing the number keys across the top of your keyboard. Press the button corresponding to the layer you would like to continue routing on. A description of the buttons follows.
T = Top
B = Bottom
1 = Inner layer 1
2 = Inner layer 2
3 = Inner layer 3
4 = Inner layer 4
S = Silkscreen top (not a routing layer)
S = Silkscreen bottom (not a routing layer)
M = Solder mask top (not a routing layer)
M = Solder mask bottom (not a routing layer)