Another battery question (lead acid)

I have a lead acid battery (picture below)
I got it and it's fairly new measuring 12.76 volts.
It came with no charger and I have NO idea how to charge it.
I'm somewhat hesitant to plug anything to it because of it's size and chemical composition.
anyways all help is appreciated.

I'd go with a commercial charger, such as:

My favourite source for this type of guidance is Battery University:

The basic information you need is printed right on the battery. It wants a float charge of 13.5 to 13.8 volts.

That's good info, but doesn't point to anything you can actually buy.
The one I posted covers that:

For Charging 12V SLA Battery:

Active State Model Output current Output voltage Bicolor LED
1.Fast Charge CC mode 3.0A 14.5V Red
2.Continue Charge CC&CV mode 3.0A or below 13.8V+/-0.20V Red
3.Stand-by charge CV mode <0.6A about 13.8V max Green