Gardening is a wonderful hobby. I suffer from depression and it helps so much to be outside just pottering around.
Don’t worry about being a novice. You definitely need drainage holes in smaller pots, and to raise them up a little so the water drains away and the roots aren’t sitting in water, which will rot them. Larger pots can cope better without them because the water will sink down to the bottom , well away from the roots. Too much water is as bad as not enough. If you buy the right plant for the right place (most good online sites will show you which plants are suitable for full sun, shade, dry conditions, damp conditions, containers etc) from a reliable nursery and look after it according to the instructions you won’t go wrong. The nurseries I mentioned (I should have given Beth Chatto a mention too) will guarantee your plants provided you follow the care instructions.
Enjoy!