First place would be pagination in PHP then peruse some of the tutorials that turn up. Find one that suits you level of knowledge.
Essentially, if your results are coming from a Mysql database then PHP will make full use of Mysqls' LIMIT clause e.g. " select name from users ORDER BY name LIMIT 20, 10 " which is like saying starting at row 20 of these results, get me the next 10 only.
Also, take a look at ZF Paginator, its so easy to use once you have it set up.