That Soldering Iron is quite cheap, but it should be OK.
(I have one like that in my truck, that I use on a Power Inverter.)
If your Tip is NOW Black, You need to clean and get it shiny, before trying to tin it again.
Maybe use an SOS pad or a fine sandpaper.
But DON'T get too aggressive, Just enough to remove the Black.
Than Turn your Iron on Again and hold the Solder to the Tip as it heats up.
Once you have it Tinned, Wipe it Frequently Between Uses, to help keep it clean.
Also Before Turning it Off, Wipe it and apply some FRESH Solder.
From RP Electronics?
Than I Assume your in Vancouver?