Excel Time Series Graph: Analyzing Trends Over Time

Time Series Graph

First select your data.

Then go to Insert > Scatter > Scatter with Smooth Lines. You will get a chart like this:

Edit horizontal axis. To edit horizontal axis right click horizontal and go to Format Axis. A tab will appear on the right.

Under axis options, change maximum to 4 and major (under units sections) to 1.

Delete horizontal gridlines. Your final graph will look like this.

Template

Further reading: 
How to Format Date and Time?
Chart with Hours
Statistical process control chart
Basic concepts 
Getting started with Excel
Cell References