<Snipped quote by Ruby>
but isnt world building also important
also what is the difference in taking part of your rp and someone elses since i am here and curious
Yes, of course, World Building is always important. Whether you're doing your own custom setting, or just trying to bring a well known setting to life (for example; comics, Star Wars, Lord of the Rings, etc). World Building includes the NPCs the characters will interact with, it includes scrubbing submitted Character Sheets to insure nothing there will 'break' the feel of whatever world your setting is based in.
But most of that work is done BEFORE the game even gets started. Hence IntChecks/OOCs threads having a fair amount of setting information included.
The difference in GMing and RPing, made simple: When you GM, you write for yourself, and everyone else. You tell a story and answer to the needs/complaints of your players. When you RP, you simply write for yourself, and maybe the person responding right after your IC post. Your character is your chief concern, and most importantly, how your character interacts with the setting and the other characters.
Whereas when you GM, every aspect of the game is your concern. Character approvals, setting, post pace, post standards, OOC communication, players dropping and adding, etc, etc. I showed up to the Guild as an Advanced RPer/writer; I showed up as a really good writer...but not a lot of RP experience. So I personally took at least a few months to RP in other folk's games so I could get a feel for how they work, and how the Guild works, before I GMed my first game.
Also, it's worth noting, that people are helpful. When I first started GMing, I picked a GM I really liked writing with and talking to and I used them as a sort of "GM mentor"--if I had questions, or just needed a soundboard, I used them. This "GM Mentor" has helped me immeasurably over the years here on the Guild, and I still count them as one of my dearest Guild friends, and favorite people to collaborate with.
So don't be afraid to find someone you think GMs how you'd want to GM...then PM them with questions. The vast majority on the Guild are insanely nice when approached in this way, so don't be shy about it.