The fix malware problems free Codex has an outline of what permissions are acceptable. File and directory permissions can be changed either through an FTP client or within the administrative page from your web host.
It will start with the basics. Try to use passwords. Use special characters, numbers, letters, and spaces and combine them to make a password. You could Find Out More use.
Should you ever want to migrate your site elsewhere, such as a new web host, you'd be able to pull this off without a hitch, and also without needing to disturb your old site until the new one was in place and ready to roll.
Note that you should only try this last step for new installations. If you would like to do it for existing installations, you have to change all of the table names inside the database.
Do your homework and some hunting, but if you are pressed for time and need to get this try the WordPress safety plugin that I use. It's a relief to know that my site (and company!) are secure.