When you're out and about, depends on your flow. Because you don't dry out, often you don't need to change it. If you do, the huuuuge booklet (in about fifty languages, just looks scary and thick at first) suggests you just rinse out with bottled water. I usually rinse with water (we have everything set up for rinsing nappies in the loo so no faff, but you could use a jug normally) and sterilise when I remember, you can boil it or cold sterilise it as often as you want, usually between periods though.

I think it's great because it's environmentally friendier than tampons, it's re-usable, it feels better and it saves money.