We could use more information on your phone. How much memory are you working with? You can find this under settings/options/memory. Please post the results. Also, what version of the OS are you using? You can find this under settings/options/about (3rd line down has that info).
To upgrade your OS, first make a backup of your phone data using the BB Desktop Manager software which should be on your computer (if not, download it). Then update your OS to the latest version which is located here:
http://www.blackberryforums.com/gene...a-english.html. Please follow the directions exactly as they say (it's not hard), and if you have any questions just ask.