On Planet Minecraft, you post skins, mods, texture packs, projects, and all that. The more views and downloads you get, the more experience you get. A view is I think like 1 or 2 experience points and a download is like 5 or something.
On Minecraft, you can get it by killing mobs like spiders and enderman. You can also buy an experience bottle if you are on a server from the shop. You left click them to throw them.
