How do I use my Nikon D50 with a 50mm 1:1.8 D lens manually?

I've always used it on Auto with a 55-200 DX Zoom but now I need to shoot some stuff at f. 22… With the 50mm fixed lens. The pose/time doesn't matter because its still life and on a tripod.
But I've lost the instruction manual and can't remember how to do it… Nor how to use the timer…

Use Aperture Priority Mode (set your lens to the smallest opening) and switch to Manual Focus if necessary too.
It will probably increase the ISO, so good lighting is needed. 3-point, or light tent for small objects.

I have found your manual, glad to return it now that I know whose it is it is here:
http://cdn-10.nikon-cdn.com/pdf/manuals/dslr/D50_en.pdf

If you need f/22, then set mode to A then turn the wheel until you get f/22. In M mode, you'll need to press the +/- button (in front of the shutter release button on the right) as you turn the wheel. I hope your lights are up to it. The timer? The button is right there in front of the shutter release button, on the left side. Press then turn the wheel to select between timer or remote.

You can download a free copy of the manual from Nikon's website.

BTW, does your D50's built-in flash still work? I have a couple of them and both flashes somehow stopped working. I've tried having the bulb replaced but the technician said it works fine so he swapped the flash module with a good one and yet nothing.

Put the camera in aperture priority. Choose the desired f/stop and take the shot