Format your SQL as something like $SQL = "SELECT * FROM xyz ..... LIMIT $start, $count". Where $start is the count to start with and $count is No of records to be displayed. 0,10 will display 1st 10 records, 10,10 gives items 10 to 19 etc...
On "Next >>" in HTML page, you may submit value for $start as $start+$count.
On "<< Prev in HTML page, you may submit value for $start as $start-$count.
Make sure that $start-$count won't go negative
Make sure that $start+$count wont go above COUNT(*) of that SQL without limit.