I replaced the coolant temperature sensor because I was getting the code for range failure on this sensor. That fixed the "check engine" issue but now my temperature gauge on the dash board is almost all the way to the right (H). It used to be right in the middle.
I bought this sensor from the auto parts store and it was listed as the one for 05 Honda Accord. Do I need to calibrate the sensor maybe?
Also, I had to drain the coolant when I was removing the sensor. I poured about a galon of the antifreeze back in the radiator. The coolant level in the white container is right in the middle. Do I need to add more coolant directly in the radiator?
Anyone has an idea what's going on?

 

It seems that I added not enough coolant.
After a half hour long drive I rechecked the coolant level and the white container was almost empty. Added more coolant and after another long drive it was below the min again. Added even more and the temperature gauge seems to stabilized nicely in the middle of the range now.

 

Messing with the coolant if you don't know what you're doing could be extremely deadly to your engine.

You said you drained the coolant? Where did you drain it? At the radiator? You should have filled the radiator to max, reservoir to high line and bled the air out of the system.

Unless you're willing to properly bleed the air out don't mess with the cooling system. You're going to have air pockets that will cause overheating. The reservoir now being low is probably the air bleeding itself out because you didn't do it properly. There's probably air still in there. Look up how to bleed coolant for your year and do it pronto.