Upload and change font

How to change the font of a specific text (for example: for Site Title Header or for the Body Text)?

Please help me, I've tried several examples from forums and similar questions but the font I uploaded wouldn't read.

for reference, i used NATIVE TemplateThank you!

@poli123

/* Change font all site */
* {
  font-family: font-name !important;
}
/* Change font Site Title */
#header h1.site-title {
   font-family: font-name !important;
}
/* Change font body */
div#page * {
   font-family: font-name !important;
}