I'm from California, which has different ways for people to start selling their art - and many types of school; also, many artists are self taught.
There are private galleries of different sorts. There are municipal galleries of different sorts, some of which have open entry shows which may or may not be juried for entry. There are art-in-the-park type shows, where you set up a booth and try to sell your wares. Sometimes people form artist groups and have group shows in different venues; one such group I know has every person in the group work on the same theme for a show. People now have their own websites and sell through them. Sometimes they join websites that do the selling for you, for a fee.
On schools, we have everything from local high schools that have night classes (or they used to) in such things as beginning spanish and beginning art. There are community colleges, which can have some good teachers, and I think it is possible to just take one class. The are colleges devoted to the arts. There are universities with art majors and graduate art departments. Some of those universities have extensions which have art classes at night for adults.
I may be forgetting something obvious, just typing as I think of things.
I suggest you start looking around at galleries and simply ask advice if the gallery people are friendly.
I've had a couple of galleries, many years apart. We talked to people who walked in off the street, but weren't always able to look at the art right then, as we also had other work to do. For years, people preferred a set of good slides of one's work in preferences to photos - we didn't care. We never gave someone a show without seeing the work in person, either by appointment with the person bring the work to the gallery, or our going to the person's studio or home. At the time I was with my last gallery, we primarily did one person shows, with the person's work filling a large room; work from other artists associated with the gallery were also shown in the rooms further back. But, many galleries do multi artist shows, especially ones that sort of combine being a gallery and a gift shop/card shop. In the last city I lived in, the whole town was pretty interested in art, and the walls of coffee shops and boutiques and beauty salons... often had some art, usually for sale. So, that is a way to start too.
So, what advice? Just talk with people..