Hi Sindhu,
Follow the below steps:
1. Create a line chart with the required dimension/measures.
2. Create a forecast.
View below solution to create a simple forecast.
https://www.edureka.co/community/44161/forecast-tableau?show=44161#q44161
![](https://www.edureka.co/community/?qa=blob&qa_blobid=15598225409657226853)
3. Not remove the forecast from the color shelf and add labels.
![](https://www.edureka.co/community/?qa=blob&qa_blobid=16936354933519367101)
4. Edit the forecast by right-clicking on the line and Go to forecast and then click on Forecast options, Edit the number of periods and prediction interval, and unselect Show prediction levels and click ok.
![](https://www.edureka.co/community/?qa=blob&qa_blobid=11135292064671512530)
5. ![](https://www.edureka.co/community/?qa=blob&qa_blobid=7177988800537282080)
Hope it helps.