In Vim, how to insert a word after regex match at the begining of next line

Question

A word needs to be injected at the beginning of each line 1. I tried the following, but obviously it does not work :g/^=/+1i/myword/

File structure:

===============
line 1
line 2
...
===============
line 1
line 2
...

Answer 1

You are almost there:

:g/^=/+1normal Imyword

Note that +1 could be shortened to + and :normal to :norm:

:g/^=/+norm Imyword

See :help :insert for why your method couldn't work and :help :normal.