how to give a user a role?

or

/ NOTE: Of course change 3 to the appropriate user ID
$u = new WP_User( 3 );

// Remove role
$u->remove_role( 'subscriber' );

// Add role
$u->add_role( 'editor' );

Super Admin – somebody with access to the site network administration features and all other features. See the Create a Network article.

Administrator – somebody who has access to all the administration features within a single site.

Editor – somebody who can publish and manage posts including the posts of other users.

Author – somebody who can publish and manage their own posts.

Contributor – somebody who can write and manage their own posts but cannot publish them.

Subscriber – somebody who can only manage their profile.