Go to park tools.com or the Park Tools YouTube channel. They have videos for derailleur adjustments and a lot of other cool stuff. Easy to follow and pretty spot on. Being a newbie, don’t get sucked in thinking you need every tool they use, they are one of the major bike tool manufacturers. What you will need is a screwdriver, metric hex wrench and maybe a needle nose pliers. While not great quality, you can find them all for under $10 combined at Harbor Freight.