To increase your maximum upload limit in WordPress (usually set at 2MB on shared hosting services) all you need to do is create a php.ini file with the following lines included...
memory_limit = 32M
upload_max_filesize = 16M
post_max_size = 16M
max_execution_time = 300
Change the values to suit your needs
Once you have created this php.ini file, drop it in your wp-admin folder and you should be good to go with a much better maximum upload limit.