I use Stitch Artist by Embrilliance for digitizing embroidery. Its one of the most user friendly programs and there are many many Stitch Artist Videos to help you get started. The online PDF manual is full of great instruction.
I used a star for my example. I open Stitch Artist (Create) and select the Design Icon. I selected the 5 point star (First one). I copied the star so now I have 2 stars in my object pane. I reduced the size of second star.
I then select both stars and right click on the objects on the screen. When you right click on objects, a popup menu appears. Select Combine With Hole.
Once you do this your object pane will show one object:
Select a node from each star....I did mine on the bottom:
Right click on one of the nodes and a pop up menu appears. Select Connect to Hole.
Now they are connected. The photo below, I have pulled them apart just temporarily so you can see where they are connected.
Now you can add your stitching. I selected satin column and then added inclinations to sharpen the stitches at the points.
You can move the nodes to widen the satin stitch....
Works with rectangles, circles.... Again, a big thank you to Harper and Brian at Embrilliance for helping me with this.