1) Watch This video how to setup.
2) copy your channel ID
3) Edit the code change the channel ID and put your channel URL Id.
4) delete <*/p*> tag from the code that show in code box.
5 put the code in your wp and other web page.
6) Enjoy Youtube Channel subscribe botton.

Subscribe Botton Example:

<script src="https://apis.google.com/js/platform.js"></script></p> <div class="g-ytsubscribe" data-channelid="UC4VYT-Tmlwr4vdcRB9i6vCA" data-layout="default" data-count="default"></div> <p>

Example2:

<script src="https://apis.google.com/js/platform.js"></script></p> <div class="g-ytsubscribe" data-channelid="UC4VYT-Tmlwr4vdcRB9i6vCA" data-layout="full" data-count="default"></div> <p>

Example3:

<script src="https://apis.google.com/js/platform.js"></script></p> <div class="g-ytsubscribe" data-channelid="UC4VYT-Tmlwr4vdcRB9i6vCA" data-layout="full" data-count="hidden"></div> <p>

Example 4:

<script src="https://apis.google.com/js/platform.js"></script></p> <div class="g-ytsubscribe" data-channelid="UC4VYT-Tmlwr4vdcRB9i6vCA" data-layout="default" data-count="hidden"></div> <p>