I have my own postfix mail server on my computer with port forwading on my router in port 25 to 25 but I still can't send mail to other servers(comcast) or from mail servers. Can someone help me?

You could start with looking at the error messages in the log files.

in ubuntu 9 where are the logfiles?

/var/log/

You might try testing port 25 to see if your ISP is blocking SMTP connections. That seems to be becoming more common. I've had several providers that blocked traffic on TCP port 25. Try telneting on port 25 to a known mail host, and you should get a prompt. If you get a "connection failed" error message, you're most likely being blocked.

example of a successful connection:
user@system> telnet mail.yahoo.com 25
Trying 192.168.1.100 ...
Connected to mail.nowhere.com.
Escape character is '^]'.
220 mail.nowhere.com ESMTP Postfix
quit
221 Bye
Connection closed by foreign host.

example of an unsuccessful connection, if the ISP close the connection cleanly:
user@system> telnet mail.nowhere.com 25
Trying 192.168.1.100 ...
telnet: connect to address mail.nowhere.com: Connection refused

if your provider just blocks the connection and doesn't close it, you'll get something like:

user@system> telnet mail.nowhere.com 25
Trying 192.168.1.100 ...
telnet: connect to address mail.nowhere.com: Connection timed out

It says the connection timed out but i can telnet my own server from the internet.

If your outbound connection attempt timed out, then that definitely points at your provider blocking outbound SMTP. I'd suggest that you call your provider and ask them if they are blocking outbound traffic on TCP port 25. Earthlink did this to me a number of years ago, and they simply turned it back on, but I've heard that doesn't always work these days. The providers claim they do this to help stop spamming from compromised hosts at people's homes, but I suspect that's an excuse, many of these providers won't open up the port unless you purchase "Business" service, or something like that, which is generally much more expensive.

I did a live chat with comcast and they said they dind't block any ports. Do
I looked on the mail quoe ant his message was here:
and other hosts like hotmail block me.

If you have a dyamic ip, most smtp servers will block you.
They will not accept connections from dynamic ip's.

i think I have static. How do i check?

Try this link:
http://www.ipaddresslocation.org/
It should show you lots of information about your public IP. If still not sure mark your actual IP. Reboot your router and try the link again. If the IP is still the same you should be static.
Most of the ISP include into the My hostname the type of connection.