You can start by getting a bunch of flower pots, depending on what you want to plant inside. It doesn’t work to plant huge trees inside unless you want to get a huge room with high ceilings to put your tree in.
They sell dwarf fruit trees in a lot of places that are great for indoor gardening.
Anyhow after you decide on how many flowerpots you need, you make sure you have holes in the bottom of the flowerpots for drainage. Many of the plastic flowerpots come with about half inch holes in the bottom for this, I like to plug up the holes a little bit with small rocks so I can put soil in the flowerpots.
Next i add the soil, 1/2 regular dirt from your yard as long as no big rocks or sticks, than the other half a good potting mix. This seems to work fine for me.
Put in seeds, there are many books on starting seeds, even at your area library . If you are starting with already growing plants, just add them to the flowerpots. I’ll be adding some links for you to purchase some books on the subject soon.
than water and follow the planting instructions on your seed packet as to watering, watch your plants grow, and Enjoy!!