Vectorising can be easy but it can also be complex. Start with a high resolution file in clear colours (black and white makes it easy).
Import the image, select it and hit the vectorise button.
You can play with the settings here, but normally you don't need to. Click OK or next or the green tick. Then click on the black colour and then the green tick. Hey presto, you have your lines.
The SMB files are a proprietary format. If you want to export them to something else, add them to a job, select them, and then use File, Export to save as a different type.
You can add symbols by creating your vector however you like, and then select it, then open the symbol library and click Add.
(Very simple explanations above. There are lots more things to find out)
GV Software Support.