Hi,
You can create the table with following SQL:
CREATE TABLE IF NOT EXISTS `#__sefaliases` (
`id` int(11) NOT NULL auto_increment,
`alias` varchar(255) NOT NULL DEFAULT '',
`vars` text NOT NULL,
`url` int(11) NOT NULL,
PRIMARY KEY (`id`),
KEY `alias` (`alias`)
);
There seems to be some problem with your upgrade process. How did you upgrade JoomSEF? You need to use the Upgrade page in JoomSEF component, not the Joomla's extension manager.