I\'ve just started using Sublime Text 2, coming from emacs.
I have a region of text selected. Within that region, I\'d like to replace all text instances of \'0\' with \
As @JOPLOmacedo stated, ctrl + F is what you need, but if you can't use that shortcut you can check in menu:
and there you have it.
You can also set a custom keybind for Find going in:
As your request for the selection only request, there is a button right next to the search field where you can opt-in for "in selection".