You don't really need to.
When people are going to give a recital of any kind they usually like to look their best. Wearing what you call "fancy clothes" is how some people do that. The important thing is to wear clothes that are comfortable and that won't be distracting.
First, you need a piano ... next, you need to take piano lessons and learn how to play the piano proficiently. Once that is done, you buy the music and play it.
First, you need a piano ... then you need to obtain the piano music, then you need to learn the piece, practice it for several months, then play it on the piano.
A piano would come in handy...
To play proficiently on the piano, you need to learn all 88 keys on the standard piano keyboard.
First, you need a piano ... then you need to find the music, purchase it, takes piano lessons, learn and practice the piece for weeks and/or months, then finally play it.
For a newbie wanting to expand their hobbies, learning to play the piano can be a good choice to make. To get started they need to purchase a piano lessons book and one of the greatest books about this subject is the, "How to Play Piano: Everything you need to Know to play the Piano" book.
Well, you need to have access to a piano, and need to know how to play the piano usually done by taking years and years of lessons, then you buy the music from the store, and you sit down, learn the piece and play it.
To play a wide range of music on the piano, you need to learn all 88 keys on the piano keyboard.
First, you need to obtain the music, then learn it, practice lots, then you will be able to play it on the piano.
Maybe a songwriter or one of those waitresses who also plays the piano at a fancy restaurant.
First, you need to purchase/obtain the music, then you need to find a piano on which to learn and practice this piece, then you play it. If it isn't arranged for piano, then you might want to make your own transcription on the piece.
You purchase the music, practice it on the piano (you may need piano lessons first, though) and then you have played it. Learning to play the piano is an art ... you can't learn to play it just from reading about it ... take lessons, and practice a lot.