Sendpress e-mails does not sent

I am just starting with Sendpress. Having problems with sending emails. They stay in the queu and are not sent…? I want the emails (200) are sent within a minute.
After i filled in the email and press sent in the screen appears the choise of email-lists (on the left side), but instead of the email the head of mij website appears and below the head big figures “404” and in the middle of 404 “not found”.
I am doing a lot of things wrong, who will help me?