Your best bet would be to go to a saw shop and pay the guy to sharpen the chain. Perhaps at the same time he would show you how to remove the chain. Don't take this next statement wrong. I'm a little skeptical of you having a chain saw at all if you cannot figure out oil/gas ratios and chain removal on your own without going to the internet. If this is indicative of your knowledge of chain saws then there is a high likelihood that you will be inquiring in the very near future about amputations and wound care. Before you use it go to this site and read...

Here is a link that might be useful: chain saw use and safety