I think when you read the article from blog , you will see link to read more full article.
with this article i will guide you how to make "read more"

firstly you must Login to your blogger account and go to dasboard
follow this step : Clik - Layout - Setting - Format - look underside , beside "Template Posting" text ,there's an empty area, into the empty area fill with the code below

Clik - Layout - Setting - Edit HTML - Check "Expand Widget"

Look and find inside box codes , the code like below:

5- Delete the code above, and replace with code below :

Click "Save" button , co saving you've mades

After that's when you make a posting so , at posting menu section ,click Edit HTML ,and automatically will be appear code like below:

All article will be appearing ,place before , and will be appear after clicking Readmore link ,placed after or like the example below:
Article appearing before clicking Readmore