Hi - you can first remove the rocks by carefully prying them at the centre using a small bottle opener (pointy end) and they should come off in chunks.

I'll also tell you that no bonsai worth its name is ever braided, tho' I know tons of those things are sold as 'bonsai'. And because you have no plant growing experience to begin with, I strongly suggest you forget the bonsai thing and just try to keep this plant alive as a plant, never mind bonsai - leave that for another day (year :) when you've done a lot more research beforehand. You can use regular potting soil with ~ 1/4 of it being perlite (bagged) but most of what you'll use is already in the pot now of course. I also strongly suggest you get help from someone who's repotted plants so you'll know what to do with roots as you encounter them and what to do with them as you repot. I'd probably get a slightly wider and shallower (by 1-2") pot and when the job's done, water and let it drain in the sink. Be very sure the new pot has 1-2 good size drain holes in it. Use any standard houseplant fertilizer every two wks according to directions. Put it in a sunny place (windowsill) and enjoy!

Good news, now is the perfect time of year to re-pot.

As Mooch said, remove those rocks.

These plants do a lot better with a fast-draining mix, otherwise they are very prone to root-rot. I use screened bark (orchid mix bark), perlite, scoria, and turface. A small amount of potting mix won't hurt. When you re-pot, remove the old potting mix completely, then carefully fill all the spaces between the roots with the fresh mix.

You could easily go to a 6-inch container.

Josh