Replace All:
:%s/foo/bar/g
Find each occurrence of 'foo' (in all lines), and replace it with 'bar'.
For specific lines:
:6,10s/foo/bar/g
Change each 'foo' to 'bar' for all lines from line 6 to line 10 inclusive.
Replace All:
:%s/foo/bar/g
Find each occurrence of 'foo' (in all lines), and replace it with 'bar'.
For specific lines:
:6,10s/foo/bar/g
Change each 'foo' to 'bar' for all lines from line 6 to line 10 inclusive.