Easy Step :
1.Find ur longer post that u want make it appears shorters and click Edit
2.U can make with 2 different way Compose button and Edit HTML button in left of ur screen(I will describe the compose button first)
3.Click Compose button then decide Where in the post u want to create interval and place ur cursor in that position
4.Once ur Cursor placed at the interval point,simply click the Insert Jump Break toolbar icon
6.For Edit HTML button just place this code <!--more--> anywhere u want the interval point placed
Note:
If U using third-party template,u will have to add a snippset of code to make the Jump break work.To do this Find ur Template Option and Click Edit HTML button andCheck Expand Widget templates button.Find this text on ur HTML code
<data:post.body/>
Once you've located that code, paste the following snippet directly below it:
<b:if cond='data:post.hasJumpLink'>
<div class='jump-link'>
<a expr:href='data:post.url + "#more"'><data:post.jumpText/></a>
</div>
</b:if >
After you've pasted in the code, click Save and then you're done!Happy Blogging^^