To import from Springpad, you need to follow a few simple steps:
1) Download the archive with your Springpad backup and unzip it.
2) Open Nimbus Note and go to File - Import - From Springpad File.
3) Press Browse and select the JSON file from the folder with Springpad backup.
4) Press OK.
5) Importing may take a long time, depending on the number of notes being imported.