How do you program the remote for an audio receiver

https://www.att.com/esupport/article.html#!/u-verse-tv/KM1047419

Use the appropriate remote programming code for your remote and the device which hopefully will be in the remote's user manual.  If you lost the remote's user manual download the appropriate pdf from here.   If there is no appropriate code for the device then you are just going to have to continue to use the device's own remote.  That's because if someone got lucky with your device and knows a code and either replies here or posted in these forums for you to search out there's no way of finding out if any exists.  

Note, no one is going to give you a specific answer unless you post the make and model of device and which remote you are using (silver, s10, s20, s30).

The instructions are there, re read the manual.

1. Find your Audio Brand and its corresponding number in the chart above.
2. Press and hold the OK and Menu keys simultaneously for three seconds until the Power key flashes red twice to confirm you are in program mode.
3. Press the Interactive key. The Power key will light up red and stay lit.
4. While pointing the remote at your audio device, press and hold down the number key for your brand. Let go of the key as soon as the audio device sound mutes.
5. Press the Mute key on the remote control to unmute the audio device. Then use the volume up/down keys to verify that the remote is controlling your audio device volume. If it does not work properly, go back to step 2 and try again.

You missed the point of my post, the manual gives the code for my receiver,
but no instructions on how to manually enter the code

No I didn't.  See above and look more closely at the user manual.  In the s10 manual Section 2B "Manually Program the Device Codes" and in the s20 manual "Setting up using manual control".

Well, if DaytonaBum won't thank you for your help, I will.

Thanks.  Maybe he hasn't check this thread as yet.