The information hasn't been posted beforehand because almost noone fires spring-guns, or cares enough about them to maintain them.
However, if you MUST waste your time maintaining something that cost you next to nothing, then do so like this:
1. look for points of contact (generally places that endure friction, or are more prone to wear) .
2. put some lube on the slide rails, and frame rails ( the little tracks that the slide moves on).
3. Don't bother too much about repeating step 1,2 because it will eventually break, like all low quality springers.
Oh, and next time, try and add a detailed description of what you have so we can help you better.