[ossiblue]

Targalid has given you the directions for adjusting the idle however, his suggestion to read up on the CIS is the most important for you. You may find the idle screw is ineffective or you do not get a smooth running engine. If so, you likely have other issues common to older CIS systems most of which are easily fixed. So this is just a heads up to do some reading and feel free to post questions here or do a search if needed.

As far as the fan belt, it is adjusted by adding or removing shims from between the pulley halves on the alternator.

If you need to tighten the belt, remove the pulley bolt and cone washer, separate the halves, remove one shim, replace the outside pulley half, put the removed shim between the pulley half and the cone washer, and tighten the nut. Test the tension. Repeat the process if you need the belt tighter, one shim at a time. (Use caution when reassembling the pulley to ensure the belt is centered and the halves are parallel.)

Important: you should have a total of 6 shims, distributed between the pulley halves and the outside washer at all times.