As my mod has grown the Creation Kit has started adding new files.

My mod now has a .bsa, bsl, ckm and the .esp files.

When I want to upload to the Nexus or to the Steam Workshop do I also have to include these files?

If so, how?

Thanks!

The ckm and bsl files are temporary files created while making a bsa and uploading to steam.
On the nexus, you only need to include the esp and the bsa.
For Steam, the CK will do it all for you - specifically, the bsa and the esp are packaged INTO the ckm file, and it is the ckm file that is uploaded to steam. But you don't need to worry about that, you can delete it - the CK will create a new one if need be.