Builders toolkit.
https://www.nexusmods.com/fallout4/mods/22808
Great place to start.
Takes you through all the baby steps for the CK - up to advanced stuff. Even if you have never used the CK, this will walk you through everything. And I mean everything. I never used the CK at all until i went through the steps that are here in this guide. I cannot promote it enough. It does what is says "on the tin"
Then, if your serious about wanting to make stuff, request an invite to the discord channel. (link for discord request is included in the above link) Here, there are loads of people than can, and will, and want to help you progress and succeed in creating an Add On Pack for SS