Hi Tom,
Wow! There's this new thing called doing an Internet search, not sure how it works, but this came up:
12vDC to 300vAC using 555
These are two circuits you could look at, the second doesn't use the 555, instead the CD4047, it's the same idea, they look interchangeable. Someone with a keener eye may be able to say if both are "good" circuits to use as a base.
12VDC to 220VAC Inverter with 555 Timer
Simple 100W inverter circuit
I really have to ask: Are you an engineer/electrician, or are you a person who has little experience and wants to make this for some reason (and do you have at least a suitable DMM to measure voltages with)?
KlausST needs to show up and write in red text: Dangerous voltages. Be careful. etc. I mean it seriously if you have little experience of circuits - a pound of preparation beats a horrible accident or just burnt circuits, so really do read up on posts #2 and #3's suggestions first, please. My apologies if you know exactly what you are doing.