This helped me quite a bit, as I am one of those people who does better when I can follow a step-by-step guide. On the main page, there, it will tell you how to get up and running with Creation Kit (both versions, so take care about which instructions you're following for Special Edition.) Once ready, there's a "tutorial hub" link, which will take you to where the most common tasks are linked, and the search box in the top right will get you the answers to a whole lot of more specific questions.
I would suggest using this in conjunction with video tutorials, like Darkfox127's series. For a task, like for example setting up Hearthfire planters, read the written tutorial then watch the video to see how it all looks. Then keep the tutorial open on another device or in the background, and refer to it as you go, to avoid missing steps.
This one is a part of it, but I am linking it separately because, even though it's a bit dated and some of the programs used might have to be sought out via google now, it's a pretty good guide to the other basic tools you'd need to do retextures and to manipulate meshes and texture assignments. Even if not retexturing, this can come in handy with helping you install replacers and fix errors in the data folder.
Lastly, probably the most helpful tips I've gotten. A. Before you make any changes, inspect a vanilla version of it, to see how the devs did it. B. When working in interior or exterior cells, hide trees, ceilings, walls, light sources, etc. to get them out of your way, by selecting them and pressing 1 twice. On the third press, they'll come back into view, but usually you will end up hiding a bunch of stuff and then bringing it all back at once, with ALT + 1 or f5. f5 is probably the simplest. If you forget when you shut down, not to worry. They're hidden, not gone, and they'll be back next time you open the cell. This is especially useful with trees and banners, which seem to jump in the way of your mouse, no matter what else you were actually trying to move.
Hope it helps.