Hey! Painting minis can be fun and become as involved or simple of a hobby as you want it to be.

Here's a list of the supplies I'd recommend (some of which you'll already have at home most likely):

• minis (duh) - I recommend staying away from metal as a beginner. Plastic or resin is a bit easier to handle and doesn't chip as easily after painting, especially in the hands of kids
• hobby knife and/or clipper - plastic and resin minis will come with some leftover bits from the production processes that need to be removed, clippers can help removing model parts from the sprues. Cheap ones will usually do imo.
• super glue or plastic cement to assemble the minis
• a basic miniature paint set - you can use regular acrylic paints but miniature specific paints have higher pigment concentrations and flow better. This makes using mini paints a lot better than other types of acrylics, especially for beginners. I'd recommend a starter set by Vallejo or AK Interactive for example as both are great paint ranges at an affordable price (and are actually among the best paints in general imo).
• You could also get a brown and a black "wash", sometimes called "shades" or "quick shades". They are special paints for easy shading which can be very fun to use for easy and impressive results
• some cheap synthetic brushes sizes 0 - 6 or so - for starting out this is more than enough imo
• DIY wet palette - video - paper towerl, tupper box with lid, parchment paper/baking paper makes a nice wet palette
• primer - I'd recommend black rattlecan primer by any miniature paints company like citadel, army painter, vallejo, ak interative etc. - otherwise paint won't stick to the models well
• matte varnish to seal the models so paint stays on when using them in games, especially when kids use them too. This can be in a rattlecan or brush on varnish.
• a nice desk lamp helps as seeing the details on a model can be quite straining on the eyes otherwise.

There is also a nice (a bit longer) video covering all the basic steps by Youtuber Squidmar here.

I hope this helps you get started. The hobby is a lot easier to get into than I expected when I got started and you can really see some huge improvements from mini to mini in those first weeks.