how to charge battery and connect battery to jayco eagle 10

Battery is fine. Although if you deep cycle a starting battery very much it will soon lose capacity. It will last longer if you camp while plugged in.

Kettle and rice cooker are not going to run off this battery very long. Incandescent lights are also a power hog. The included converter looks like a slow charger (poor) for using a generator.

You will have a hard time going 3-7 days without some upgrades and additional equipment.