Box display flex code example

Example 1: display flex css

.class {
  display: flex;
}

/* use display: flex to turn CSS element into a flexbox */

Example 2: flexbox

Please read flexbox & grid in CSS TRIX, 
make hands-on project watching (WESBOS videos - it's really useful)
also try [FLEXBOX - froggy] and [GRID - garden] games