How to import a stitch library
If you want to import a new user stitch library and someone has sent you their .smlib file, make sure you save it somewhere memorable (perhaps in your Workspace folder). Open Stitchmastery and click Tools/Stitchmastery and then Preferences. Make sure the Stitchmastery menu in the left hand column is extended and click Stitch Libraries. Choose the User Libraries tab and click Import. Use the Browse button to locate the stitch library, which will have the file extension .smlib.
Read more at User Stitch Libraries