Hi Paul.
Your laptop won't run DaVinci. Not properly anyway. DaVinci is a very resources hungry editor and will only render out smooth video on the most powerful of computers. I tried it on an i5 laptop which had a NVIDIA Cuda graphics card and it had 8gig memory, and it struggled to render 1080 video smoothly. Absolutely no chance with 4K stuff. DaVinci runs an awful lot better on this computer I have now (4K graphics card, 4.2 MHz processor and 16gig memory) but even on this machine I can still see some judder withe 4K renders! IMHO I think you would have some difficulty finding a half decent free editor that will run on an i3, but you could try a prog called ShotCut (do a google for it). At one time I tried it and it ran well on my laptop.
If you are prepared to pay for an editor a good reasonably cheap one that is fairly simple to learn and would probably work on your laptop is one called 'Filmora' (do a google). I use Filmora. Not the best editor out there...there are better ones...but good enough to justify the cost.