I did attestation of my US certificate two one and half yrs ago. Boy! thats a long and lengthy process.anyway here is the link to have you started.

http://qatar.usembassy.gov/document_authentications.html

Keep in mind that after you done all the steps of the above link, you have to send the attested certificate to Qatar Embassy in Washington and after that you can take all the paper to US embassy here in Doha to finish the process.

Qatar embassy thing is missing from US embassy website but trust me without this step they dont take it. It happened to me.

Good luck.