Minecraft forge download error message. You must manually run 1.7.2 first?

I'm trying to download some mods but I need minecraft forge ad it comes up with that message. So how do I run 1.7.2, I have no idea how to change it. I'm new to minecraft pc
Thanks.
Also can I change it back to 1.8 after and still use the mods? It won't mess up my worlds will it?

Guest

Well, if you want to change to 1.7.2, go to your profile, push edit, and there will be a button thingy with the thing (not sure what its called xD) ex: 1.8,1.2,1.6.4 blah blah. I'm sure you can use mods at 1.8 but the mods need to say if its useable in the update

alyssa