I have a honeywell programmable thermostat and I want to onlt run tne fan, what do I need to do ?

There should be a switch or setting that says fan auto, or fan on. You want to put it to fan on. However, in order for this option to work, there must be a wire (usually green) between the g terminal on the stat, and the g terminal on the furnace control board. Let us know what you find.

Don't know what model you have but mine has a slide button marked "fan" with 2 positions-auto and on. Moving switch to on starts the fan.