First of all, Outlook Express is a mail client. That means that it has to talk to a mail server to get and send a copy of your mail. This is like you dropping postal mail in a post office box or picking it up at the post office. And like snail mail, you have to know your post office. There are a few ways to connect to a mail server (Post Office). IMAP is one way, but not used much any more (other than possible still HOTMAIL, and a few others). Today's standard is POP3 for receiving mail and SMTP for sending mail. They are protocols (think of it as secret handshakes, or standard instructions) that most mail clients support and understand.
In any case, you need to configure the client to connect to the correct servers. It appears that you have either kept the defaults or put in just the names of the mail protocols, not the names of the servers. Typically the POP3 server is named pop.servername.com and the SMTP server is name smtp.servername.com (although that is just a common naming theme and can be quite different.) For example: comcast mail servers are pop.comcast.net and smtp.comcast.net (POP3 and SMTP respectively)
Check with the mail service to see what the names of the servers are first, then in Outlook Express go to Tools, and then Accounts, and edit the properties for the account you want to use.
You can have as many email accounts as you want, and Outlook Express will sync the mail with the servers if you have it checked to do it. Just remember that if you remove the mail from the server, you will not be able to see it in your web browser mail once you have synced it with Outlook Express. If you travel a lot or use many PCs to check your mail, you might want to uncheck this option, and save the mail on the mail server, however, that means you will have to periodically do housecleaning to keep the volume low and not run out of storage space.