Blogger is a blog-publishing service that allows multi-user blogs with time-stamped entries. It offers two easy options for integrating the publisher's script.

After:
You submit your website for validation in Adcash's publisher panel, and the Website has been validated.

You create a zone for your website with the intended format.

When you have created a zone for your website, Javascript code will be provided that would be inserted on your website.

Example:

First Option: 
Placing the script in a WordPress Layout gadget.

Add a Gadget:
In Your Blogger Admin Dashboard,
Select Layout

Click on Add Gadget:
Locate and add HTML/JavaScript Gadget.

Insert JS script provided in the Adcash publisher's panel into the code box

Enter a title (Optional).
Tick to make Gadget Visible.
Press Save.

NEXT:
Drag-and-drop the new gadget to where you want it to appear.

Click on Save Arrangement.
NB: 
If you also have a mobile theme for your blog, you would need to enable the gadget specifically for it.
Also, always make gadget Visible.

Second Option: 
Place the script inside a post
Let's Navigate:
Select Post

Click on Add New Post
Switch into HTML mode.

Insert JS script provided in the Adcash publisher's panel into the code box

Switchback to Compose mode, to continue editing your Article.

NB.
Don't Place the script inside a Compose Mode, posting might let you see the advertisement within the post editor, it might also show as a blank box or a blank line instead.

Blogger script integration tutorial (Interstitial)