I found an old bluetooth headset and charger but no instructions so m wondering how do i pair a cellular innovations headset hfblu-fp1 to my phone

Usually because the purchaser didn't read the instructions or because the instructions are badly written from Chinese. This is an eBay special. I wrote this Tip on connecting Bluetooth devices which mentions the step that is always missed.

https://www.fixya.com/support/r26362721-pairing_bluetooth_devices

iEssentials Bluetooth FP1 Headset, USB Car Charger ...

https://www.ebay.com > itm

iEssentials Bluetooth FP1 Headset, USB Car Charger Included ( IE-HFBLU-FP1 ) · Item Information · Item specifics · Shipping and handling · Sales Tax for an item # ...
US$12.95 · ‎In stock

Check what bluetooth protocol or stack they have. Old headsets could be on level 1, while the newest phones are on level 4.2.
They most of the time can be downward compatible, but not for the extremes.
Be aware Apple has even less tolerance for other protocols. And headsets, for a phone, are the ones with a microphone and a little speaker. Not the ones for music.
Check both manuals for compatibility.
Here is more about bluetooth :
Bluetooth Wikipedia the free encyclopedia

bluetooth - charging mashine problem bring it to recheck the charger

That usually means it isin pairing mode. Charging some headsets from extended periods can sometimes reset the device requiring you to pair the device again.

the problem seems to be the charging box. if the red light goes off relatively quickly after you place the bluetooth in the box then it is not gaining a charge. you have a warranty with this item that you can claim by following the instructions on the warranty card provided in the package.

go to your phone and turn on your blue tooth.that might be the problem.

with your phone STILL ON remove the battery, wait 5-10 seconds replace battery..power up phone and try to pair. should work after phone resets itself.

headset won't pair with me phone and i have tried 0000 and 1234 and 12345

For Cellular Innovations Mini Blue HFBLU-AX1C.
To Pair with Your Phone....

1. Turn OFF Bluetooth Headset
2. With Headset within 1 Ft of your phone, hold down power key for about 8 seconds until indicator light blinks in red and blue color quickly (in pairing mode)
3. Search bluetooth device through your mobile phone.
4. Select HFBLU-AX1C in the bluetooth device list and enter the password 1234.

For Cellular Innovations Mini Blue HFBLU-AX1C.
To Pair with Your Phone....

1. Turn OFF Bluetooth Headset
2. With Headset within 1 Ft of your phone, hold down power key for about 8 seconds until indicator light blinks in red and blue color quickly (in pairing mode)
3. Search bluetooth device through your mobile phone.
4. Select HFBLU-AX1C in the bluetooth device list and enter the password 1234.