How to create Spfx package solution

 Steps to create SharePoint Framework(Spfx) Package 

1. Open Spfx solution in Visual Studio Code (VSCode).
2. Delete release and sharepoint folder from solution if exist
3. Open Config ->package-solution.json file, update id with new guid and increase version number and save it.
4. Open src->webparts\yoursolutionname->yoursolutionnameWebpart.manifest.json file, update id with new guid and save it.
5. Increase version number in package.json if last 3rd digit in version number in package-solution.json file is changed and save it.
6. Open new terminal from Terminal tab in top menu bar in VSCode. shortcut to open new terminal - Ctrl+Shift+`
7. Run command gulp clean.
8. Run command gulp build.
9. Run command gulp bundle --ship
10. Run command gulp package-solution --ship
11. You will see SharePoint folder in solution. Open that folder in file explorer. You will see yoursolutionname.sppkg file there.