You can certainly plant one of the Erica's in your container, or possibly more than one if it is small, but don't plant Calluna vulgaris, which is the heather in your photo as it will get too tall and rank. Not sure why anyone would want to plant moss but the 3rd photo doesn't actually show moss! That said the Erica would rapidly swamp the other plant out. Note Erica's do not flower year round but they do retain their leaves. Mind you neither does Mexican fleabane for that matter!

Are you limited to the three plants you mention?
If you have no plant knowledge at all are you wanting to learn or do you want something that will more or less look after itself? The plants that you mention are all pretty now but they will not look like that all year round and you will find that people who have attractive flower displays in containers usually change the plants round, having a spring display, a summer one and something for winter.
Many plants only flower for a few months and then have a long rest.

Alternatively you could have an evergreen shrub, perhaps one with gold and green or silver and green leaves that will be the same all the year round and would need very little maintenance.

Have a think about what effect you want and come back to us with a bit more information - but don't panic, there's plenty of time to get it right! People here will be very ready to give you all the help you need.

I was offered some Mexican fleabane, Erigeron karvinskianus by a neighbour but refused as the plant will quickly spread by self-seeding into every crack and crevice and becomes a garden pest. Having said, my neighbour and many other gardeners adore it.

I don't think you can go wrong with the Mexican fleabane. It flowers for at least 6 months and is so pretty and dainty. It does seed around into cracks, and that's fine by me!

Not with me though!

the moss plant you are showing looks like a moss phlox. they are a good container plant.

The Erigeron didn't spread at all for me - lasted a few years and then went to the great compost heap in the sky...don't think it got enough sun.

Isn't it weird how some plants are loved and some hated by gardeners? Personally I love the Erigeron and it does seed sometimes, I think it likes a softer soil than we have! My hate is Japanese Anemones.

Absolutely love my cheerful reliable Erigeron and wouldn't be without it!
Recently visited a swish cafe which had it planted in attractive pots on the outside tables--looked great!
Yes it self seeds into crevices but not madly and it's easy to pull out if necessary. Bees love it too!