JRFlurry

I know this is gonna sound probably really dumb but I'm still a total noob at all of this. How can I back up my site in case anything goes wrong? I get nervous installing mods and such because if my site goes down I'm screwed. After investing over 200 hours in site building that would make for a really bad day!! haha. I don't know if it makes any difference but my site is basically a forum built with SMF 2.0 RC3. If you wanna look at the site itself its in my signature. Thanks for any help you can give!!