Renewing openssl certificate(for newbies???)

[phobot <piter90@gmail.com>]

Sorry if this is too annoying, but I'm kind-a new and have some auto
generated certificates which I need to replace since the openssl
issues. If someone can help me out I'll be very thankful.

Starting Nmap 4.11 ( http://www.insecure.org/nmap/ ) at 2008-05-19
17:04 EEST
Interesting ports on localhost (127.0.0.1):
Not shown: 1667 closed ports
PORT     STATE SERVICE
21/tcp   open  ftp
22/tcp   open  ssh
25/tcp   open  smtp
53/tcp   open  domain
80/tcp   open  http
110/tcp  open  pop3
113/tcp  open  auth
143/tcp  open  imap
783/tcp  open  spamassassin
953/tcp  open  rndc
993/tcp  open  imaps
995/tcp  open  pop3s
3306/tcp open  mysql

Nmap finished: 1 IP address (1 host up) scanned in 0.084 seconds

I've tried to set them up as securely as possible (with my rather poor
skills) so I need some advice on renewing the certificates any advice
at all will be appreciated.
Thank you for your time.