I'll just assume you've never done a chainring swap before? It's pretty easy if you know what you're doing and have tools.
You need to remove the chain first. After that, remove the crank + chainring from your BB (if you've got a square tapered BB, you'll probably need that great Park tool that we all love). Once you've removed that, unscrew the crank bolts to separate the chainring from the crank.
Now just put the new chainring on the crank, and put it all back on the bike. You might need to add some length to your chain, just don't make it too loose.